Corriente Resources Inc.: Form 6-K - Prepared by TNT Filings Inc.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer
Pursuant to Rule 13a-16 or 15d-16 of
the Securities Exchange Act of 1934

For the month of December, 2006

Commission File Number 001-32748

CORRIENTE RESOURCES INC.
(Translation of registrant's name into English)
 
520 - 800 West Pender Street, Vancouver, British Columbia, CANADA V6C 2V6
(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F _____             Form 40-F     X     

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ____

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ____

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes _____             No     X       

If "Yes" is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82-_______________

DOCUMENTS INCLUDED AS PART OF THIS REPORT

Document  
   
1.

Technical Report - Update on the Copper, Gold, and Silver Resources and Pit Optimizations: Mirador and Mirador Norte Deposits - November 30, 2006

 

 

 
MINE DEVELOPMENT ASSOCIATES  
MINE ENGINEERING SERVICES  

Technical Report Update on the
Copper, Gold, and Silver Resources
and
Pit Optimizations:
Mirador and Mirador Norte Deposits

MIRADOR PROJECT, ECUADOR

for

CORRIENTE RESOURCES INC.

November 30, 2006

George Sivertz, P. Geo.
Steven Ristorcelli, P. Geo., C.P.G.
Scott Hardy, P. Eng.

775-856-5700

210 South Rock Blvd.
Reno, Nevada 89502
FAX: 775-856-6053

 
MINE DEVELOPMENT ASSOCIATES  
MINE ENGINEERING SERVICES  
     
C O N T E N T S    
       
1.0 SUMMARY 1
  1.1 Introduction 1
  1.2 Geology and Mineralization 3
  1.3 Sampling, Quality Assurance/Quality Control and Check Sampling 4
  1.4 Metallurgical Testwork 5
  1.5 2005 Mirador Deposit Mineral Resource Estimate 6
  1.6 2006 Mirador Norte Resource Estimate 9
  1.7 2006 In-Pit Resource, Mirador Norte Deposit 10
  1.8 Recommendations 11
2.0 INTRODUCTION AND TERMS OF REFERENCE 13
  2.1 Introduction 13
  2.2 Terms of Reference 13
3.0 RELIANCE ON OTHER EXPERTS 15
4.0 PROPERTY DESCRIPTION AND LOCATION 16
  4.1 Property Location 16
  4.2 Mineral Tenure 16
  4.3 Permits and Agreements 23
  4.4 Environmental Impact Assessment 25
5.0 ACCESS ROUTES, CLIMATE, PHYSIOGRAPHY AND INFRASTRUCTURE 27
  5.1 Access Routes 27
  5.2 Climate 27
  5.3 Physiography 27
  5.4 Infrastructure 27
6.0 HISTORY 29
  6.1 Exploration History 29
  6.2 2004 Mirador Deposit Mineral Resource Estimate (AMEC) 31
7.0 GEOLOGICAL SETTING 34
  7.1 Regional Geology 34
  7.2 Local and Property Geology 34

775-856-5700

210 South Rock Blvd.
Reno, Nevada 89502
FAX: 775-856-6053

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves  
Corriente Resources Page 2
   
     
8.0 DEPOSIT TYPES 38
9.0 MINERALIZATION 39
10.0 EXPLORATION 41
  10.1 2000 42
  10.2 2001 42
  10.3 2002 42
  10.4 2003 42
  10.5 2004 42
  10.6 2005 42
  10.7 2006 43
11.0 DRILLING 44
12.0 SAMPLING METHOD AND APPROACH 53
13.0 SAMPLE PREPARATION, ANALYSES, AND SECURITY 55
  13.1 Sample Preparation and Analyses 2000-2004 55
  13.2 Sample Preparation and Analyses 2005-2006 55
  13.3 Sample Security 56
14.0 DATA VERIFICATION 57
  14.1 Introduction 57
  14.2 Quality Assurance/Quality Control Programs, Mirador 2005 and  
    Mirador Norte 2003-2006 57
    14.2.1 Summary and Conclusions 57
    14.2.2 Sample Preparation and Analysis 58
    14.2.3 Duplicate Analyses on Pulps and Coarse Rejects – Mirador Deposit (2005) 59
    14.2.4 Duplicate Analyses on Pulps and Coarse Rejects – Mirador Norte 67
    14.2.5 Standard Reference Samples – Mirador Deposit 72
    14.2.6 Standard Reference Material – Mirador Norte Deposit 75
  14.3 Mirador Norte Database Audit – 2006 78
  14.4 Sample Integrity 78
  14.5 Drill Site Field Checking 81
  14.6 Mirador Norte MDA Check Samples 81
  14.7 Mirador Norte Metallurgical Composite Sample Comparison 82
15.0 ADJACENT PROPERTIES 84
16.0 MINERAL PROCESSING AND METALLURGICAL TESTING 85
  16.1 Introduction: Mirador Deposit 85
  16.2 History of Mirador Deposit Metallurgical Testwork 85
  16.3 Mirador Deposit Flowsheet 87
  16.4 Mirador Norte Metallurgy 88
   
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17.0 MINERAL RESOURCE ESTIMATES 90
  17.1 Introduction 90
  17.2 Corriente Geologic Model 90
  17.3 Sample Coding and Compositing 93
  17.4 Density 94
  17.5 Resource Model and Estimation 97
  17.6 Resources 109
  17.7 Discussion, Qualifications, Risk and Recommendations 117
18.0 OTHER RELEVANT DATA AND INFORMATION 118
  18.1 Introduction 118
  18.2 Floating Cone Analyses 118
  18.3 Production Schedules 120
  18.4 Economic Model 121
19.0 REQUIREMENTS FOR TECHNICAL REPORTS ON PRODUCTION AND DEVELOPMENT
  PROPERTIES 124
20.0 CONCLUSIONS 126
21.0 RECOMMENDATIONS 128
22.0 DATE AND SIGNATURE PAGE 129
23.0 REFERENCES 130
24.0 AUTHOR'S CERTIFICATE AND SIGNATURE PAGE 132
     
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T A B L E S    
Table 1.1 Criteria for Resource Classification 7
Table 1.2 Mirador Resource Estimate Summary 8
Table 1.3 Mirador Norte Deposit Indicated and Inferred Resources 10
Table 1.4 Floating Cone Parameters 11
Table 4.1 Registration Data for Mirador Concessions 18
Table 4.2 Annual Conservation Patent Fees Payable for Mineral Concessions in Ecuador 21
Table 4.3 List of Major Permits Required for the Mirador Project 23
Table 6.1 Mirador Deposit Mineral Resource Summary – 23 September 2004 33
Table 10.1 Statistics and History of Mirador and Mirador Norte Drilling Programs 41
Table 11.1 List of Drill Holes Surveyed in Field – Mirador Norte 44
Table 14.1 Statistics of the Duplicate Samples 62
Table 14.2 Absolute Value of the Relative Difference between Sample Pairs 62
Table 14.3 List of Re-Analyzed Batches - Mirador 72
Table 14.4 Descriptive Statistics of the Standard Reference Material 75
Table 14.5 List of Drill Holes Surveyed in Field – Mirador Norte 81
Table 14.6 List of Independent Samples – Mirador Norte 82
Table 14.7 Comparison of Metallurgical Sample and Drill Sample Grades (Mirador Norte) 82
Table 17.1 Coding and Description of the Geologic Model 91
Table 17.2 List of Specific Gravity Values Used in Model 95
Table 17.3 Mirador: Estimation Parameters for Copper by Mineral Domain 99
Table 17.4 Mirador: Estimation Parameters for Gold by Mineral Domain 101
Table 17.5 Mirador: Estimation Parameters for Silver by Mineral Domain 102
Table 17.6 Mirador Norte: Estimation Parameters for Copper by Mineral Domain 103
Table 17.7 Mirador Norte: Estimation Parameters for Gold by Mineral Domain 104
Table 17.8 Criteria for Resource Classification 110
Table 17.9 Mirador Copper, Gold and Silver Resources – Measured 113
Table 17.10 Mirador Copper, Gold and Silver Resources – Indicated 113
Table 17.11 Mirador Copper, Gold and Silver Resources – Measured and Indicated 114
Table 17.12 Mirador Copper, Gold and Silver Resources –Inferred 114
Table 17.13 Mirador Norte Copper and Gold Resources – Indicated 115
Table 17.14 Mirador Norte Copper and Gold Resources – Inferred 115
Table 17.15 Mirador Norte Copper and Gold Resources – by Material Type 115
Table 18.1 Floating Cone Parameters 119
Table 18.2 Floating Cone Results 119
Table 18.3 25,000 Tonnes per Day Production Schedule 121
Table 18.4 50,000 Tonnes per Day Production Schedule 121
Table 18.5 Economic Model Inputs 122
Table 18.6 Economic Model Results, 25,000 tpd Case (8% discount rate) 122
Table 18.7 Economic Model Results, 50,000 tpd Case (8% discount rate) 123
Table 18.8 25,000 tpd Case Initial Capital 123
     
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F I G U R E S    
Figure 4.1 Location Map 17
Figure 4.2 Concession Location Map 19
Figure 4.3 Detailed Map of the Mirador Concessions 20
Figure 4.4 Detailed Map of the Mirador Property Rights 22
Figure 4.5 Map of Mirador Project Concessions and Bosque Protector Condor Limits 26
Figure 7.1 Typical Mirador Deposit Cross Section (450) - Geology 35
Figure 7.2 Drill Core Photo of DDH M64 Showing Low RQD 37
Figure 7.3 Drill Core with Unaltered Anhydrite (Below the Gypsum Front) 37
Figure 11.1 Mirador Drill Hole Location Plan 45
Figure 11.2 Mirador Norte Drill Hole Location Plan 46
Figure 11.3 Drill-hole Collar Marker 49
Figure 11.4 Core Recovery Statistics by Material Type - Mirador 50
Figure 11.5 RQD Recovery Statistics by Material Type - Mirador 50
Figure 11.6 Core Recovery Statistics by Material Type – Mirador Norte 51
Figure 11.7 RQD Recovery Statistics by Material Type – Mirador Norte 51
Figure 12.1 Core Saw Facility 54
Figure 14.1 Copper Duplicate Assays – Pulps 60
Figure 14.2 Gold Duplicate Assays – Pulps 60
Figure 14.3 Copper Duplicate Assays – Coarse Rejects 61
Figure 14.4 Gold Duplicate Assays – Coarse Rejects 61
Figure 14.5 Relative Differences of Copper Duplicate Assays – Pulps 63
Figure 14.6 Relative Differences of Gold Duplicate Assays – Pulps 63
Figure 14.7 Relative Differences of Copper Duplicate Assays – Coarse Rejects 64
Figure 14.8 Relative Differences of Gold Duplicate Assays – Coarse Rejects 64
Figure 14.9 Absolute Value of the Relative Difference of Copper Duplicate Assays – Pulps 65
Figure 14.10 Absolute Value of the Relative Difference of Gold Duplicate Assays – Pulps 65
Figure 14.11 Absolute Value of the Relative Difference of Copper Duplicate Assays –Coarse Rejects.

66
Figure 14.12 Absolute Value of the Relative Difference of Gold Duplicate Assays –Coarse Rejects 66
Figure 14.13 Relative Difference of Copper Duplicate Assays – Pulps 68
Figure 14.14 Absolute Value of the Relative Difference of Copper Duplicate Assays – Pulps 68
Figure 14.15 Relative Difference of Copper Duplicate Assays –Coarse Rejects 69
Figure 14.16 Absolute Value of the Relative Difference of Copper Duplicate Assays –Coarse Rejects.

69
Figure 14.17 Relative Difference of Gold Duplicate Assays – Pulps 70
Figure 14.18 Absolute Value of the Relative Difference of Gold Duplicate Assays – Pulps 70
Figure 14.19 Relative Difference of Gold Duplicate Assays –Coarse Rejects 71
Figure 14.20 Absolute Value of the Relative Difference of Gold Duplicate Assays –Coarse Rejects 71
Figure 14.21 Standard MS1 Checks – Copper - Mirador 73
Figure 14.22 Standard MS1 Checks – Gold - Mirador 73
Figure 14.23 Standard MS2 Checks – Copper - Mirador 74
Figure 14.24 Standard MS2 Checks – Gold - Mirador 74
Figure 14.25 MS1 Round Robin and Sampling Results, Cu (%), (Mirador Norte) 76
Figure 14.26 MS1 Round Robin and Sampling Results, Au (ppm), (Mirador Norte) 76
Figure 14.27 MS2 Round Robin and Sampling Results, Cu (%), (Mirador Norte) 77
     
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Technical Report Update on the Copper, Gold, and Silver Resources and Reserves  
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F I G U R E S    
Figure 14.28 MS2 Round Robin and Sampling Results, Au (ppm), (Mirador Norte) 77
Figure 14.29 Core Recovery and Grades and Rock Characteristics (Mirador Norte) 79
Figure 14.30 RQD and Grades and Rock Characteristics (Mirador Norte) 79
Figure 14.31 Hole Depth and Grades and Rock Characteristics (Mirador Norte) 80
Figure 14.32 Elevation and Grades and Rock Characteristics (Mirador Norte) 80
Figure 14.33 Metallurgical Sample Grade Comparison: Copper (Mirador Norte) 83
Figure 14.34 Metallurgical Sample Grade Comparison: Gold (Mirador Norte) 83
Figure 16.1 Simplified Mirador Flowsheet 89
Figure 17.1 Schematic Illustration of Rock and Mineral Zones Used for Estimation - Copper 92
Figure 17.2 Schematic Illustration of Rock and Mineral Zones Used for Estimation–Gold and Silver

92
Figure 17.3 Mirador Norte Density by Down-hole Depth 96
Figure 17.4 Mirador Norte Density by Elevation 96
Figure 17.5 Mirador: Typical Cross Section (450) with Block Grades – Copper 105
Figure 17.6 Mirador: Typical Cross Section (450) with Block Grades - Gold 106
Figure 17.7 Mirador Norte: Typical Cross Section (200) with Block Grades – Copper 107
Figure 17.8 Mirador Norte: Typical Cross Section (200) with Block Grades - Gold 108
Figure 17.9 Mirador: Typical Cross Section (450) with Block Classification 111
Figure 17.10 Mirador Norte: Typical Cross Section (200) with Block Classification 112
     
A P P E N D I C E S
Appendix A Letter Report Regarding the Mirador Property by Trejo Rodriguez & Asociados, Abogados.
Appendix B Mirador and Mirador Norte Drill Hole Locations, Orientations and Lengths
Appendix C Sample Descriptive Statistics for Copper, Gold, and Silver - Mirador and Mirador Norte
   
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MINE DEVELOPMENT ASSOCIATES  
MINE ENGINEERING SERVICES  

1.0     SUMMARY

1.1     Introduction

Corriente Resources Inc ("Corriente") owns the Mirador Project, located in southeastern Ecuador. The Mirador Project includes the Mirador and Mirador Norte copper-gold-silver deposits. The Mirador deposit is the most advanced of the two, but exploration of the Mirador Norte deposit has now been brought to the point where there is sufficient information to support a resource estimate.

Corriente Resources Inc. engaged Mine Development Associates ("MDA") in August 2006 to provide an updated mineral resource and pit optimizations for the Mirador Norte deposit, and an updated Technical Report for its Mirador Project in southeastern Ecuador. Steven Ristorcelli, Principal Geologist for MDA, served as the Qualified Person responsible for preparing the mineral resource. This Technical Report was prepared by Steven Ristorcelli and George Sivertz, P.Geo., Senior Geologist, OreQuest Consultants Ltd. This report provides a summary of Mirador Project work conducted since 2000, and an update and review of the Mirador Project activities that took place in 2005 and 2006.

The last Canadian National Instrument ("NI") 43-101-compliant Technical Report for the Mirador project was completed by MDA and was filed on SEDAR by Corriente on May 19, 2006. Since that time, Corriente has advanced the Mirador Norte deposit by completing a 39-hole, 6,781-m core-drilling program and commissioning a copper, gold, and silver resource estimate and pit optimizations.

The Mirador property is centered 10 km east of the Rio Zamora (Zamora River) in the Zamora-Chinchipe Province of southeastern Ecuador. The eastern property boundary is adjacent to the Ecuador-Perú border. The concessions are approximately 340 km south of Ecuador's capital city of Quito and 70 km east-southeast of the city of Cuenca. The Mirador property comprises ten mineral concessions that cover an area of 9,928 hectares (99.28 km sq2). The concessions are in two separate blocks; the main Mirador block, which consists of eight contiguous concessions, is located to the east of two separate contiguous concessions, Mirador 3 and Mirador 4. The main Mirador block covers both the Mirador deposit and the Mirador Norte deposit, which is located three km northwest of the Mirador deposit.

Billiton Ecuador B.V., now BHP Billiton S.A. ("Billiton") began regional exploration in southeastern Ecuador in 1994 and identified a number of possible porphyry copper targets in the region. In April 2000, Billiton and Corriente entered into an agreement covering 230 sq km of mineral concessions in the southern part of the region, including the area of the Mirador property.

775-856-5700

210 South Rock Blvd.
Reno, Nevada 89502
FAX: 775-856-6053

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves  
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Corriente has carried out exploration on the Mirador property since April 2000. The majority of the work focused on the Mirador deposit, and it included geological mapping, geochemical soil sampling, rock chip sampling and diamond core drilling. To date 36,284 m of core drilling in 143 diamond drill holes has been completed. Corriente, through its wholly-owned subsidiary companies in Ecuador, holds a 100% interest in the Mirador property. Billiton holds a 2% Net Smelter Royalty interest in the Mirador deposit.

Corriente discovered the Mirador Norte deposit in 2003. The work completed at Mirador Norte since that time included geological mapping, geochemical soil sampling, rock chip sampling, and 13,605 m of core drilling in 68 diamond drill holes. Corriente, through its wholly-owned subsidiary companies in Ecuador, holds a 100% interest in the Mirador Norte property. Billiton also holds a 2% Net Smelter Royalty interest in the Mirador Norte deposit.

At both the Mirador and Mirador Norte deposits, copper mineralization, primarily chalcopyrite, occurs with lesser gold and silver as disseminations and stockwork associated with a multiple-phased granodiorite intrusive system.

In November 2003, Corriente commissioned AMEC Americas Ltd ("AMEC") to be the primary consultant for the preparation of a bankable feasibility study for the Mirador project, which was based on the Mirador deposit alone. Knight Piésold Ltd was responsible for the design of a tailings management facility and related infrastructure, and Merit Consultants International Inc. provided study coordination, project planning/scheduling, and capital cost estimates. The Feasibility Study Report was filed on the Canadian SEDAR (System for Electronic Document Analysis and Retrieval) web site on May 13, 2005.

Corriente expanded its technical database in 2005 by completing 11,935 m of core drilling in 52 holes in the Mirador deposit. This program was in large part aimed at better defining the distribution of weakly mineralized porphyry dikes and breccias, which account for most of the lower-grade zones in the deposit. Another benefit was improved resolution of the distribution of higher-grade supergene copper mineralization. The geological data from the drill holes, together with new information from outcrops exposed during the construction of new drill trails, helped to confirm and refine contacts of the porphyry dikes, particularly in the northern sector. A few holes targeted the breccia dikes in the north part of the deposit, to better locate and define their contacts and to explore for potentially economic copper mineralization along their margins. The 2005 holes did not intersect any sizeable new dikes, or locate any important new areas of mineralization, so little revision of the geological model was required.

In the fourth quarter of 2005, Corriente retained MDA to prepare an updated mineral resource estimate for the Mirador deposit and to conduct pit optimization studies. The purpose of the mineral resource estimate update was to incorporate the new data from the fifty-two drill holes completed in 2005 into the resource model. MDA relied upon certain results of previously published work, and used procedures similar to those used by AMEC in the preparation of the 2004 mineral resource estimate. In its report titled "Technical Report Update on the Copper, Gold and Silver Resources and Pit Optimizations, Mirador Project, Ecuador", dated May 18, 2006, MDA reported Measured and Indicated Mineral

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Resources of 437,670,000 tonnes grading 0.61% Cu, 190 parts per billion (ppb) gold, and 1.5 parts per million (ppm) silver, at a 0.40% Cu cutoff grade. Inferred Mineral Resources, also at a 0.40% Cu cutoff, were stated as 235,400,000 tonnes grading 0.52% Cu, 170 ppb gold, and 1.3 ppm silver. The MDA estimate placed more material in the Measured and Indicated resource category than was reported by AMEC in 2004, at a slightly lower grade. These changes were the direct result of the inclusion of new data from the 2005 infill-drilling program.

In 2006, Corriente completed 6,781 m of drilling in 39 core holes in the Mirador Norte deposit. The program was designed to provide geological and grade information to support a resource estimate. Corriente engaged MDA in August 2006 to provide a mineral resource estimate for the Mirador Norte deposit, in compliance with the CIM Mineral Resource and Mineral Reserve definitions referred to in National Instrument ("NI") 43-101. MDA was also instructed to prepare a Technical Report for the Mirador Project to include both the Mirador and Mirador Norte deposits.

1.2     Geology and Mineralization

The copper-gold-silver mineralization of the Mirador deposit is hosted dominantly by Late Jurassic granodiorite and intrusive breccia phases of the Zamora Batholith. Both early- and late-stage hornblende feldspar dikes can also be mineralized. The main copper mineral at Mirador is chalcopyrite; there is lesser chalcocite. Mineralization is present as disseminations and fracture-fillings within the host rock.

Near the center of the Mirador mineralized system is a large body of breccia, interpreted to be an intrusive pipe or diatreme. This early-stage mineralized breccia is composed of angular fragments of porphyry dikes, Zamora granite, and quartz-vein fragments.

Weakly developed zones of enriched supergene copper lie beneath a leached "cap," and a mixed transition zone separates the two.

The sequence of mineral deposition at Mirador has been divided into early-stage molybdenum, early-stage copper ± gold, late-stage copper-gold, and a final weak polymetallic vein stage. Both copper-gold depositional events are dominated by chalcopyrite, with traces of native gold. Trace amounts of molybdenite are present in early-stage quartz veins that have a preferred east-west orientation. These veins occur as stockwork in both Zamora granite and early porphyry dikes.

The geology of the Mirador Norte deposit is similar to that of Mirador, three kilometers to the southeast. Mirador Norte mineralization also consists mainly of disseminated and stockwork chalcopyrite +/-chalcocite in granodiorite of the Zamora Batholith and, to a lesser extent, in northwest-striking hornblende feldspar porphyry dikes.

At Mirador Norte, there is also a superficial leached zone from zero to forty meters thick overlying a secondary enrichment blanket, averaging fourteen meters thick. The secondary enrichment zone has chalcocite coatings on chalcopyrite and pyrite. In many holes the transition from leached to enriched is

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marked by a mixed zone with centimeter to meter-size areas with remnant sulfides within the leached zone. The enriched zone grades into primary, disseminated chalcopyrite mineralization. Higher-grade areas are associated with structurally controlled, fine-grained, dark-gray silica flooding which can contain more than 5% chalcopyrite locally. Copper grades are similar in both granodiorite and porphyry dikes, although at the south margin of the deposit the copper grades in porphyry show some variation.

1.3     Sampling, Quality Assurance/Quality Control and Check Sampling

In all the drilling campaigns at Mirador and Mirador Norte, Corriente used consistent strategies for sampling, sample preparation, and sample analysis. Split drill core samples were sent to preparation facilities in Ecuador, and 100-gram pulp sub-samples were shipped to analytical laboratories in Vancouver, Canada. Copper was analyzed by atomic absorption spectroscopy ("AAS") methods, and gold was determined by fire assay with an AAS finish. The names of the laboratories used and the details of sample preparation and analysis are provided in the pertinent sections of this report.

The quality assurance/quality control ("QA/QC") procedures used by Corriente became more sophisticated with successive drill campaigns. The early exploratory drill programs (2000-2002) did not incorporate fully adequate QA/QC procedures. To compensate for this, 5% of the sample pulps from the Mirador deposit drill programs were sent to ALS Chemex in Vancouver, Canada in 2004 for re-analysis. The copper and gold grades from the re-analyzed check samples compared well to the grades from the original samples. Consequently, all of the original Mirador deposit sample assays were considered sufficiently accurate to be used for mineral resource estimation purposes.

A more comprehensive QA/QC program was adopted by Corriente in 2004, following procedures recommended by AMEC. AMEC reviewed the duplicate sample analyses and concluded that the analytical results for copper indicated that the drill core sampling, sample preparation, and analytical procedures in use would lead to good quality copper analytical results for all samples. However, AMEC also noted that the gold data for the Mirador deposit pulp duplicate samples indicated that, for 90% of the samples, there is an average difference of 15% between the gold grades of the pulp duplicate samples and the grades of the original pulp samples. AMEC concluded that this reflected a relatively low level of precision and suggested that the causes of the effect were probably the relatively small weight of the sample shipped to the assay laboratory (100 grams), and the small fire assay aliquot weight (30 grams).

AMEC completed a data quality check on 5% of the sample database used for its 2004 resource estimation. The data were found to be of excellent quality and adequate for AMEC's resource estimation purposes.

The 2005 drilling program at the Mirador deposit involved the drilling of 11,935 m in 521 core holes (M91 to M141). Because of this drilling, 3,592 additional assayed drill intercepts were added to the drill hole assay database, which now consists of 22,317 assays in 143 core holes. During a visit in 2005,

________________
1 This includes one abandoned hole.

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MDA reviewed the results of the 2005 drilling program but did not take independent check samples from the 2005 drill holes. MDA did take independent samples from prior drilling campaigns.

The 2006 drilling at Mirador Norte totaled 6,781 m in 39 core holes. The Mirador Norte drill-hole assay database contains 4,238 copper assays and 4,233 gold assays in 68 holes. In a visit to Mirador Norte in September 2006, MDA reviewed the results of the 2006 and previous drill programs and took 17 check samples of split core from the 2003-2006 drill programs, as well as two check samples from surface exposures near the center of the deposit.

For the 2005 drilling program at Mirador, and the 2006 drilling program at Mirador Norte, Corriente generally followed the QA/QC guidelines recommended by AMEC.

The sample preparation procedures for both drilling programs are appropriate and well done, and the assays and analyses are of good quality. Based on the results of the analyses of standard samples inserted into the sample stream, there does not appear to be any significant bias in the analytical data. The results from the inserted blank samples indicate that the sample preparation procedures are conducted with appropriate care. Copper analyses of pulp duplicates reproduce well, while gold fire assays of pulp duplicates show modest variability. Although MDA does not believe that the modest variability in the reproducibility of gold assays has instilled any material bias or skewed the results, it is suggested that this be investigated with a set of metallic screen sample assays.

1.4     Metallurgical Testwork

The following refers to the Mirador deposit and is quoted verbatim from AMEC (2004).

A significant amount of metallurgical testwork has been undertaken on mineralized samples from the Mirador porphyry copper-gold porphyry deposit since 2002. SGS Lakefield Research (Lakefield), in Lakefield, Ontario carried out the main program of feasibility testing between December 2003 and September 2004. This included flowsheet development and mineralogical and recovery variability mapping programs on a total of about 3,000 kg of split diamond drill core from twenty drill holes and at various depths across the deposit. Overall this represents a reasonable spatial distribution of the expected metallurgy across the deposit.

The mill flow sheet selected for Mirador will be a conventional copper-gold porphyry flowsheet, with relatively coarse primary SAG and ball mill grinding to about 150 µm followed by copper rougher flotation, concentrate regrind to 25 µm, and cleaner flotation and dewatering. The process will be designed to treat 25,000 t/d. Concentrates produced are predicted to average 30% copper at a recovery of 91%. Gold recovery is expected to average 47%. A laboratory analysis of concentrates indicated that no significant deleterious penalty element impurities were present.

Additionally, metallurgical test work has been planned at Mirador Norte. MDA has reviewed the metallurgical sample locations that were chosen to characterize the various mineralized zones in that deposit. Based on this quick assessment of the sample locations, it seems the samples are well chosen.

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The supergene samples are distributed regularly and throughout that zone. There were no samples of mixed material. The primary mineralization was well-sampled in the main part of the deposit, but the smaller northwest branches were not sampled; the northwest part of the deposit has a much smaller tonnage, contained in two separate limbs. MDA suggests that some testing should be done on uncomposited samples to assess any changes in metallurgical characteristics spatially throughout the deposit.

1.5     2005 Mirador Deposit Mineral Resource Estimate

In 2005, Corriente requested that MDA complete a resource update for the Mirador deposit. The motivation for the update was the inclusion of the 52 new drill holes that were completed in the Mirador deposit in 2005. MDA relied on previous work and used procedures similar to those used by AMEC in the original work in 2004, unless evidence existed suggesting that new procedures should be used. The final results conform to CIM standards.

Resource estimation utilized a combination of mineral and lithologic domains defined in wireframe solids that were constructed by Corriente. Gold, silver, and copper generally occur together, and so are modeled in a similar manner except in the enriched, mixed, and leached zones. In these zones gold and silver were modeled similarly but distinctly from copper. Specific gravity values used were similar to those used in previous modeling efforts, except that there were additional specific gravity data, and a 2% reduction factor was applied to account for sample-selection bias.

MDA estimated the resource using inverse distance to the fourth power, with a maximum of 14 samples per block and a maximum of four samples per hole. Search ranges varied depending upon the zone or lithology being estimated and reached 200 m. Resource classification criteria are presented in Table 1.1. A summary of the resources is presented in Table 1.2.

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Table 1.1 Criteria for Resource Classification

MIRADOR

All – Measured

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 20

Hypogene – Indicated

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 100

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 35

Enriched (supergene) and Mixed – Indicated

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 75

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 35

All material not classified above is Inferred

MIRADOR NORTE

All – Measured

Minimum no. of samples /minimum no. of holes / maximum distance (m)

None

Hypogene – Indicated

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 100 *

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 50 **

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 35

Enriched (supergene) and Mixed – Indicated

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 75

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 35

Material not classified above is Inferred unless beyond 50 m of a sample outside the 0.12% Cu shell

Leached – modeled but unclassified; all Leached material is considered to be waste

* inside the 0.12% Cu shell; ** outside the 0.12% Cu shell

It is important to note that the deepest drill hole samples are from elevations of approximately 850 m and are mineralized. MDA has reported Inferred resources to the 750-m elevation but has modeled below this level to elevations of 650 m. Results below the 750-m elevation are not included in the reported resource.

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Table 1.2 Mirador Resource Estimate Summary

Total Measured

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 52,610,000 0.65 753,000,000 210 360,000 1.6

2,770,000

 

            

 

Total Indicated

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 385,060,000 0.60 5,134,000,000 190 2,380,000 1.5

18,760,000

 

            

 

Total Measured and Indicated

        

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 437,670,000 0.61 5,887,000,000 190 2,740,000 1.5

21,530,000

 

            

 

Total Inferred

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 235,400,000 0.52 2,708,000,000 170 1,250,000 1.3

9,900,000

 

            

 

Hypogene Measured

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 50,880,000 0.64 717,640,000 210 340,000 1.6

2,650,000

 

            

 

Hypogene Indicated

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 375,150,000 0.60 4,954,310,000 190 2,310,000 1.5

18,130,000

 

            

 

Hypogene Measured and Indicated

        

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 426,030,000 0.60 5,671,950,000 190 2,650,000 1.5

20,780,000

 

            

 

Hypogene Inferred

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 233,240,000 0.52 2,680,480,000 170 1,240,000 1.3

9,850,000

 

            

 

Supergene* Measured

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 1,710,000 0.94 35,280,000 220 12,000 2.0

112,000

 

            

 

Supergene* Indicated

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 9,650,000 0.83 176,190,000 210 60,000 2.0

610,000

 

            

 

Supergene* Measured and Indicated

        

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 11,360,000 0.84 211,470,000 200 72,000 2.0

722,000

 

            

 

Supergene* Inferred

          

 

Cutoff

 Tonnes Cu (%) lbs Cu Au (ppb) oz Au Ag (ppm)

oz Ag

0.40

 1,033,000 0.67 15,185,000 170 5,600 1.3

44,000

* Supergene includes mixed and enriched; no leached material is tabulated in Measured, Indicated or Inferred

*total Measured plus Indicated resources were calculated from rounded Measured and rounded Indicated resources and hence some apparent differences are rounding related.

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1.6     2006 Mirador Norte Resource Estimate

Corriente requested in August 2006 that Mine Development Associates (MDA) complete a resource update on the Mirador Project, and specifically on the Mirador Norte deposit, which lies about 3 km northwest of the Mirador deposit. The incentive for the update was the completion of 39 new drill holes at Mirador Norte in 2006. The Mirador Norte drill-hole assay database contains 4,238 copper assays and 4,233 gold assays in 68 holes.

The work done by MDA included a review of Corriente's geologic model and a QA/QC analysis, resource estimation, pit optimizations, and pit design.

A combination of material types, mineral domains, and lithologic codes was used to control grade estimation and assign density values for Mirador Norte. Material-type domains consist of the leached, mixed, and enriched zones in the weathered profile. For copper, mineral domains included grade shells and lithologic groups (pre-mineral dikes, post-mineral dikes, and post-mineral breccias) in the hypogene mineralization. Copper was modeled separately in each of the three weathered zone material types. Gold and silver were modeled identically to copper in the hypogene material using the same copper-grade shells, but were modeled differently from copper in the weathered zones. One of the most important geological differences between Mirador Norte and Mirador is that the dikes at Mirador Norte do not appear to materially affect the metal distributions.

In the hypogene material, the main grade shell, used for copper, gold, and silver, is defined by the change from grades dominantly above ~0.2% Cu to grades dominantly below ~0.2% Cu. A clear, albeit gradational (~0.12% Cu to ~0.4% Cu) separation is shown on quantile plots of the copper distribution. To compensate for the gradational changes in grade, two additional shells were manually defined at ~0.12% Cu and ~0.4% Cu.

Two grade shells (~0.12% Cu and ~0.4% Cu) were used to code samples, while only one shell (~0.2% Cu) was used for controlling the estimation and model block coding. Those samples lying outside the 0.4% Cu shell were used to estimate blocks outside the 0.2% Cu shell while those samples lying inside the 0.12% Cu shell were used to estimate grades inside the 0.2% Cu shell. By coding and using samples in this manner, gradational changes were instilled in the model around the 0.2% Cu grade shell. Sample compositing was done to six-meter lengths, after capping and honoring all material types, grade shells, and lithologic contacts. Overall, the mineralization style of the Mirador Norte deposit is sufficiently evenly distributed to require little capping or estimation grade-projection restrictions.

For Mirador Norte, MDA estimated three models for copper and three for gold; these were a kriged model, an inverse-distance squared model and a nearest-neighbor model. The comparison was considered good; for the final reported resource MDA used an inverse distance power of three (ID3). Because of the low silver grades and the relatively few samples with silver assays, modeling results are not reported for silver.

There is no Measured material at Mirador Norte. This is in part because the drill spacing is still relatively wide and because this is the first resource estimate for Mirador Norte. The resource for the Mirador Norte deposit is presented in Table 17.13.

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Table 1.3 Mirador Norte Deposit Indicated and Inferred Resources

Indicated Resource

        

%Cu Cutoff

 Tonnes %Cu lbs Cu Au ppb

oz Au

0.40

 171,410,000 0.51 1,921,000,000 89

489,000

 

        

 

Inferred Resource

      

 

%Cu Cutoff

 Tonnes %Cu lbs Cu Au ppb

oz Au

0.40

 45,820,000 0.51 513,000,000 68

101,000

1.7     2006 In-Pit Resource, Mirador Norte Deposit

MDA used the Medsystem© Lerchs-Grossmann "floating cone" algorithm to produce open-pit cone shells using the parameters shown in Table 1.4. Only Measured and Indicated materials were allowed to make a positive economic contribution; Inferred material is considered waste. The cutoff grade for the base case ($1.00/lb Cu price), assuming only copper revenue, is 0.37% Cu. Because recovered gold contributes value, the actual cutoff is slightly lower depending on the gold grade.

MDA designed an ultimate pit using the base-case floating cone (Cu $1.00/lb, Au $400/oz) as a template. Haul roads were designed with a maximum 10% grade and a width of 22 m. This should accommodate haul trucks of 90-tonne capacity, which are about 7-m wide.

AMEC reported preliminary pit slope angles and designs for the Mirador deposit in the 2005 feasibility study (AMEC, 2005). These slopes, adjusted for inclusion of ramps, were used in the floating cone runs for Mirador Norte.

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Table 1.4 Floating Cone Parameters

Item

Value

Copper Processing

Mill recovery %

  

91.4%

Concentrate grade %

  

30%

Concentrate moisture %

  

8%

Concentrate losses %

  

0.25%

Concentrate transport $/WMT

 $

81.62

Concentrate transport $/DMT

 $

88.72

Smelting $/DMT

 $

75.00

Smelter recovery %

  

96.5%

Refining $/lb

 $

0.08

 

  

 

Gold Processing

Mill recovery %

  

47%

Smelter payable %

  

95%

Refining $/oz

 $

6.00

 

  

 

Process cost with G&A $/DMT

 $

3.90

Mining $/DMT

 $

0.89

 

  

 

Copper price $/lb

 $0.65-$1.50

Gold price $/oz

  

$400

 

  

 

Overall pit slope angles

  

35°-42°

 

  

 

DMT = Dry Metric Tonne

  

 

WMT = Wet Metric Tonne

  

 

1.8     Recommendations

MDA and Sivertz believe that Mirador is a property of merit. For the Mirador Norte deposit specifically, it is recommended that certain work be completed:

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The cost of this work would be approximately US$150,000, excluding drilling costs, which could add approximately US$250,000.

For the Mirador deposit:

For the Mirador Project:

The ongoing engineering, cost estimation, and environmental/social baseline work should be completed, to support the bankable Feasibility Study currently being prepared by SNC-Lavalin. As of the effective date of this report, this work is all underway; it will be reported in the SNC-Lavalin BFS:

Estimated costs for the previously described engineering work would be approximately $150,000. An estimate of costs for the full range of Feasibility Study engineering and construction work is beyond the scope of this report. Corriente reports that it has budgeted approximately $22 million for Engineering, Procurement, Construction and Management ("EPCM") through the end of 2006.

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2.0     INTRODUCTION AND TERMS OF REFERENCE

2.1     Introduction

Corriente Resources Inc. ("Corriente") engaged Mine Development Associates ("MDA") in the fourth quarter of 2005 to provide an updated mineral resource estimate for the Mirador deposit at Corriente's Mirador Project in southeastern Ecuador. The work entailed estimating mineral resources for the Mirador deposit in compliance with the CIM Mineral Resource and Mineral Reserve definitions referred to in National Instrument ("NI") 43-101. The work also involved the preparation of a Technical Report as defined in NI 43-101 and in compliance with the format set out in 43-101F1. The Technical Report was entitled "Technical Report on the Copper, Gold and Silver Resources and Pit Optimizations, Mirador Project, Ecuador", and was filed on SEDAR by Corriente in May 2006. Steven Ristorcelli, P.Geo., Principal Geologist for MDA, served as the Qualified Person responsible for preparing the resource estimate. The Technical Report was prepared by Steven Ristorcelli and George Sivertz, P.Geo., Senior Geologist, OreQuest Consultants Ltd. Steven Ristorcelli visited the Mirador property from January 4 to January 7, 2005. George Sivertz did not visit the Mirador property.

Corriente engaged MDA in August 2006 to provide a mineral resource estimate for the Mirador Norte deposit, in compliance with the CIM Mineral Resource and Mineral Reserve definitions referred to in National Instrument ("NI") 43-101. MDA was also instructed to prepare an updated Technical Report for the Mirador Project to include both the Mirador and Mirador Norte deposits.

The present updated Technical Report presents a resource estimate and pit optimizations for the Mirador deposit. It retains the content of the NI 43-101 Technical Report titled "Technical Report on the Copper, Gold and Silver Resources and Pit Optimizations, Mirador Project, Ecuador", dated May 18, 2006. Steven Ristorcelli, P.Geo., Principal Geologist for MDA, served as the Qualified Person responsible for preparing the resource estimate. This Technical Report was prepared by Steven Ristorcelli and George Sivertz, P.Geo., Senior Geologist, OreQuest Consultants Ltd. Steven Ristorcelli visited the Mirador property in August 31 to September 2, 2006.

2.2     Terms of Reference

MDA and Sivertz are not associated or affiliated with Corriente Resources Inc, EcuaCorriente S.A. ("EcuaCorriente"), ExplorCobres S.A. ("ExplorCobres", formerly named Minera Curigem S.A.), or any related companies. Any fees paid to MDA or Sivertz for the work done or preparation of this Technical Report are not dependent in whole or in part on any prior or future engagement or understanding resulting from the conclusions of this report. The fees are in accordance with industry standards for work of this nature.

MDA completed a NI 43-101-compliant resource estimate for the Mirador deposit in 2005, and conducted pit optimization studies and a review of the quality assurance/quality control procedures used by Corriente in the 2005 Mirador deposit drilling program. The sections of the present report that

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discuss these studies (Sections 14, 17, and the pertinent sections of the Summary, Conclusions, and Recommendations) are based on the work done by MDA in 2005.

MDA completed a NI 43-101-compliant resource estimate for the Mirador deposit in September 2006, and conducted pit optimization studies and a review of the quality assurance/quality control procedures used by Corriente. The sections of this report that discuss the Mirador Norte studies (Sections 14, 17, and the pertinent sections of the Summary, Conclusions, and Recommendations) are based on the work done by MDA in 2006.

The sections of this report that discuss other aspects of the Mirador project rely on information set out in the following reports:

AMEC Americas Limited, 2004: Technical Report, Mirador Project. Morona Santiago (sic) Province, Ecuador. AMEC Americas Limited Technical Report prepared for Corriente Resources Inc, October 22, 2004.

AMEC Americas Limited, 2005: Mirador Copper Project Feasibility Study Report. May 2005.

Dawson, J.M., and Makepeace, D.K, 2003: Mirador Project, Corriente Copper Belt, Southeast Ecuador. Order-of-Magnitude Study, Part 1, Technical Report. February 2003.

Makepeace, D.K, 2001: Corriente Copper Belt Project, Southeast Ecuador, Order-of-Magnitude Study (Preliminary Assessment Technical Report), June 22, 2001.

Makepeace, D.K, 2002: Mirador Project, Corriente Copper Belt, Southeast Ecuador. Preliminary Assessment Technical Report, February 12, 2002.

Makepeace, D.K, 2002: Mirador Project, Corriente Copper Belt, Southeast Ecuador. Preliminary Assessment Technical Report, September 3, 2002.

P&T Asesores Legales, Abogados 2006: Letter Regarding Certain Corporate Matters and the Status of Title to the Mining Concessions in Ecuador. Prepared for Corriente Resources Inc, May 25, 2006.

Trejo Rodriguez & Asociados, Abogados 2006: Letter Report Regarding the Mirador Property. Prepared for Corriente Resources Inc, October 19, 2006.

The report is also based in part on personal communications with Mr. Ken Shannon, P. Geo., Chairman and C.E.O. of Corriente Resources Inc, Mr. John Drobe, P.Geo., geologist for Corriente, and other field geologists who worked at Mirador in 2005 and 2006. It also draws on information provided in other geological and technical reports listed in the References section of this report. The writers have carefully reviewed all of the information provided by Corriente and believe the information to be reliable. All measurement units used in this report are metric, and currency is expressed in US dollars unless stated otherwise. The coordinate system in use on the property and in all maps and references in this report is UTM zone 17 S, datum Provisional SAD 1956. The estimated costs in the Recommendations sections (1.6 and 21.0) include Ecuadorian taxes where applicable.

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3.0     RELIANCE ON OTHER EXPERTS

MDA and Sivertz have not personally reviewed the land tenure, are not Qualified Persons with regard to land tenure in Ecuador, and have not independently verified the legal status or ownership of the properties or underlying option agreements. The law firm of P&T Asesores Legales, an independent law firm, provided the writers with legal opinions on land tenure, environmental liabilities, and the status of permits as of May 25, 2006. All metallurgical information and reporting are adapted or quoted verbatim from information published in reports by AMEC (2004, 2005).

The summaries of the Mirador Project environmental and social baseline studies in this report are based on information stated in the report titled Mirador Copper Project Feasibility Study Report, dated May 2005 (AMEC Americas Limited).

The results and opinions expressed in this report are conditional upon the aforementioned environmental, geological and legal information being current, accurate, and complete as of the date of this report, and the understanding that no information has been withheld that would affect the conclusions made herein. The writers reserve the right, but will not be obliged, to revise this report and conclusions if additional information becomes known to them subsequent to the date of this report. The writers will assume no responsibility for the actions of Corriente in distributing this report.

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4.0     PROPERTY DESCRIPTION AND LOCATION

4.1     Property Location

The Mirador property is centered 10 km east of the Rio Zamora (Zamora River) in the Zamora-Chinchipe Province of southeast Ecuador, adjacent to the border with Perú (Figure 4.1). The concessions are approximately 340 km south of Ecuador's capital city of Quito and 70 km east-southeast of the city of Cuenca. The center of the Mirador concession group has UTM coordinates 9,604,200 N and 785,000 E (UTM Zone 17S, Provisional South American Datum 1956). The ten concessions cover an area of 9,928 hectares. The concessions are registered with the National Directorate of Mining and have not been legally surveyed.

4.2     Mineral Tenure

Billiton Ecuador B.V., now BHP Billiton S.A. ("Billiton") began exploration in southeastern Ecuador in 1994 and identified a number of possible porphyry copper targets in the region. In April 2000, Billiton and Corriente entered into an agreement covering 230 sq km of mineral concessions in the southern part of the region, including the area of the Mirador property. Under the agreement, Corriente could earn a 70% interest in each of the Billiton projects by completing a feasibility study and meeting certain financial and work commitments. At the completion of each feasibility study, Billiton could elect to back-in for a 70% interest by providing production financing, retain a 30% working interest, or dilute to a 15% Net Profit Interest ("NPI").

Corriente also entered into an exploration management arrangement where Lowell Mineral Exploration ("Lowell") could earn up to 10% of Corriente's interest in certain properties in exchange for managing the exploration of the properties.

In December 2002, Corriente announced that it had received notice from Billiton that the Mirador property was to be separated from the existing copper-gold joint venture in Ecuador, and that the exploration concessions were to be transferred to Corriente. Billiton was to retain no back-in rights, but had the option to retain its 30% participating interest in the Mirador property or revert to a 2% Net Smelter Royalty ("NSR"). Billiton elected to revert to the 2% NSR interest. At this time, Lowell held a 10% interest in Corriente's Mirador project. Corriente, in December 2003, granted Lowell the option to exchange its 10% interest in the Corriente mineral concessions, including Mirador, for a 100% interest in the Warintza property. In June 2004, Lowell exercised that option. Corriente, through its wholly-owned Cayman Island-based subsidiary, which in turn controls the companies in Ecuador, now holds a 100% interest in the Mirador property. BHP Billiton holds a 2% NSR interest in the Mirador property, specifically for the mining areas in concessions MIRADOR 1, MIRADOR 1A, MIRADOR 2, MIRADOR 2A, CURIGEM 18, CURIGEM 18 EAST, CURIGEM 19, and CURIGEM 19A (CAYA 36 has been transferred to Minera Midasmine S.A., a Corriente-related company, but carries the same royalty). The MIRADOR 1 and MIRADOR 2 concessions encompass the Mirador and Mirador Norte deposits. Corriente reports that for the Mirador property, the 2% NSR royalty held by BHP Billiton can be reduced to 1% if Corriente makes a payment of $2 million to BHP Billiton.

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Figure 4.1 Location Map

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The locations of the ten individual concessions that make up the Mirador property are shown in Figure 4.2 and Figure 4.3. Figure 4.2 shows all of Corriente's holdings in the region and Figure 4.3 shows only those concessions that are the subject of this report. The state code numbers, area in hectares, property registration dates and ownership of the Mirador concessions are as indicated in Table 4.1 (P&T Asesores Legales 2006). All concessions are now held by EcuaCorriente S.A. ("EquaCorriente" (Table 4.1), since those that were formerly held by Curigem S.A. were transferred to EcuaCorriente. EcuaCorriente is fully owned by Corriente through its wholly-owned Cayman Island-based subsidiary (P&T Asesores Legales 2006; Appendix A). According to information supplied by Corriente, the Mirador deposit is located along the boundary between the MIRADOR 1 and MIRADOR 2 concessions. The Mirador Norte deposit is located three kilometers northwest of the Mirador deposit, in the northwest part of the MIRADOR 1 (capitalization consistent with Registration Documents and with sec 4.2) concession.

The concessions cover an area of 9,928 hectares (99.28 sq km). All the concessions are within Zamora-Chinchipe Province. Two of the concessions, MIRADOR 3 and MIRADOR 4, are not contiguous with the main eight-concession Mirador block (Figure 4.3).

According to Ecuadorian Mining Law, concessions registered against title to mining properties have a term of 30 years, which can be automatically renewed for successive 30-year periods, provided that the registered concession holder files a written notice of renewal before the expiry date (P&T Asesores Legales 2006).

Table 4.1 Registration Data for Mirador Concessions

Concession Code Hectares Owner Registration
  number     Date
MIRADOR 1 500807 2,105 EcuaCorriente S.A. February 7, 2003
MIRADOR 1 Este 501181 295 EcuaCorriente S.A. "en tramite"
MIRADOR 2 500805 880 EcuaCorriente S.A. February 7, 2003
MIRADOR 2 Este 501182 320 EcuaCorriente S.A. "en tramite"
CURIGEM 18 4768 1,600 EcuaCorriente S.A. August 23, 2001
CURIGEM 18 Este 500806 800 EcuaCorriente S.A. February 7, 2003
CURIGEM 19 4769 2,350 EcuaCorriente S.A. August 23 2001
CURIGEM 19 Este 501183 550 EcuaCorriente S.A. "en tramite"
MIRADOR 3 500976 1,020 EcuaCorriente S.A. May 12, 2005
MIRADOR 4 501023 8 EcuaCorriente S.A. January 9, 2006
TOTAL   9,928    

Note: Caya 36, a concession that had been listed in this table in previous reports has been transferred to Minera Midasmine S.A.; "en tramite" means that the applications for these concessions have passed the first review stage between October 27 and October 29, 2006 and are waiting to be finalized.

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Figure 4.2 Concession Location Map
(From Corriente)

Caya 36 has been transferred to Minera Midasmine S.A.

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Figure 4.3 Detailed Map of the Mirador Concessions
(From Corriente)

Caya 36 has been transferred to Minera Midasmine S.A.

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Each year, owners of mining concessions in Ecuador must pay an "annual conservation patent fee" for each hectare of area that is covered by their concessions. The fees are payable during the month of March. When the appropriate fees are paid, the registration of each concession is renewed in the name of the present holder for another one-year term. The patent fees are shown in Table 4.2 table below (P&T Asesores Legales 2006). The ten Mirador concessions are currently in good standing with respect to the payment of the conservation patent fees; the next payments are due in March 2007 (Trejo Rodriguez & Asociados, 2006). . The annual fees payable for the ten Mirador concessions in March 2007 total $18,828.00

Table 4.2 Annual Conservation Patent Fees Payable for Mineral Concessions in Ecuador

From (Year of To (Year of Registered Conservation Patent Fee per
Registered Ownership) Ownership) hectare per year (US$)
     
First Third 1.00
Fourth Sixth 2.00
Seventh Ninth 4.00
Tenth Twelfth 8.00
Thirteenth Onwards 16.00

Corriente has acquired copies of the land maps that show the surface rights holdings in the Mirador area (Figure 4.4). The surface rights for all land that may be affected by proposed mining, construction sites, dumps, tailings dams and other infrastructure needed for the Mirador project have been purchased by Corriente, or are in the process of negotiation for purchase, or are being registered and verified. Figure 4.4 illustrates the status of surface rights acquisition. The different colors show the status of the surface rights. Gray represents areas with independently owned surface rights, and pink indicates areas that have been purchased by Corriente. The areas that are in the process of being negotiated or acquired by Corriente are shown in magenta.

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Figure 4.4 Detailed Map of the Mirador Property Rights
(From Corriente)

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4.3     Permits and Agreements

For the exploration phase of the Mirador property, all the required permits are included in the approved exploration-phase Environmental Impact Statement ("EIS") that is on file with the Ecuadorian government. The EIS is an annual permit that is reviewed at year-end. For any mine development, as opposed to exploration activities, another document known as an EIA report must be filed and approved by government authorities.

The Mirador mining EIA and all supporting documents were submitted to the Ministry of Energy and Mines in Quito, Ecuador, in December 2005. This EIA did not include Mirador Norte. The EIA covers both the environmental aspects of proposed mining operations at Mirador, and community and social plans associated with the Mirador project. The Ecuadorian government approved the EIA on May 4, 2006 and the letter acknowledging receipt of the bond was received by the Ministerio De Energía y Minas (Ministry of Mines) on June 12, 2006. Given demonstrated economic viability, the Mirador EIA will need to be extended to cover the potential environmental impacts generated by incorporating the Mirador Norte deposit into the Mirador mine plan. Because of recent mine planning changes, Corriente submitted a revised EIA to the government on September 29, 2006. The envisioned changes to the mine plan, according to Corriente, have a smaller impact on the environment. The government, by law, has 45 days to respond to the EIA submission. A list of some important permits required for the Mirador project is presented in Table 4.3.

Table 4.3 List of Major Permits Required for the Mirador Project
(From Corriente, 2006)

Permit Granting Institution Requirements Estimated Time for Approval
Environmental Ministry of Energy and Approval of EIA by Approved May 4, 2006
License (EIA) Mines/ Ministry of both Ministries. Revised EIA submitted on Sept
  Environment Payment of license 29, 2006
    fees.  
Permit to Ministry of Environment Approval of EMP, Valid for two years. To be
Discharge   payment of fees, obtained after one year of
    compliance with EMP operation. Estimated time to
    and regulations. obtain the permit: is 60 days.
Permit to Modify National Council for    
Water Courses Hydrological Resources Depends on EIA  
  (Consejo Nacional de amendment approval Dec 2006
  Recursos Hídricos) (Nov 2006)  
Permit to Use Joint Command of Logistics Compliance with safety  
and Transport Management/Naval and Air regulations and  
Explosives Zone Command Squad Ministry of defense  
  (Dirección de Logística del application Dec 2006
  Comando Conjunto/    
  Comandos de Brigada y de    
  las Zonas Naval y Aérea)    
Health and Ministry of Labor Presentation of Estimated time to obtain the
Safety Permit   Company's Heath and permit is 45 days.
    Safety Plan.  
   
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The following discussion of the Ecuadorian environmental permitting and approval process is quoted verbatim from the report titled Feasibility Study Report, Mirador Project, Ecuador, by AMEC Americas Limited (AMEC, 2005).

The Mirador project is located within the Cordillera del Condor. This area is considered ecologically important because of its high biological diversity and presence of endemic species.

Ecuador's environmental legislation is extensive and their requirements for early stage operations i.e., exploration, are well defined. Ecuador is one of the few Latin American countries that have adopted an EIA process for exploration activities. Argentina, Chile, and Perú have adopted a similar process to conduct environmental assessments for early stage exploration.

Under Ecuadorian Mining Law, the Ministry of Energy and Mines handles the environmental approval system for new mining projects. Mining concession holders are required to complete environmental impact studies and environmental management plans to prevent, mitigate, rehabilitate, and compensate for environmental and social impacts as a result of their activities. These studies are approved by the Ministry of Energy and Mines Sub secretary of the Environment.

Terrambiente, a Quito-based environmental firm, has completed an environmental baseline assessment for the Mirador Project. Baseline data collection commenced in March 2004 and has been ongoing through the study period.

The environmental approval process is summarized as follows:

[three bulleted points were removed as they were deemed incorrect by Corriente environmental staff)

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4.4     Environmental Impact Assessment

The firm of Terrambiente, a Quito-based environmental firm, completed an environmental baseline assessment for the Mirador project (AMEC, 2005). Baseline data collection commenced in March 2004 and has continued since that time. The following activities, related to ongoing environmental and baseline studies, are being conducted at the Mirador Project (EcuaCorriente, 2006):

MDA spent time in EcuaCorriente's Quito office discussing the project. EcuaCorriente staff believes that while the area is sensitive, causing increased costs and environmental efforts, the challenges are manageable.

On March 23, 2005 (Registro Oficial, Organo del Gobierno del Eucador), a forest preserve (Bosque Protector Condor) was designated. This preserve lies along the border with Perú and covers a portion of the MIRADOR 1, MIRADOR 2, CURIGEM 18 EAST, CURIGEM 19 and CAYA 36 concessions (Figure 4.5). While this forest designation does not preclude exploration and mining, there will be more stringent environmental regulations and permitting, which will have to be approved by both the Minister of Mines and Energy and the Minister of the Environment.

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Figure 4.5 Map of Mirador Project Concessions and Bosque Protector Condor Limits
(from Corriente)

Caya 36 has been transferred to Minera Midasmine S.A.

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5.0     ACCESS ROUTES, CLIMATE, PHYSIOGRAPHY AND INFRASTRUCTURE

5.1     Access Routes

Access to the Mirador property from Quito, the capital city of Ecuador, can be gained by road or by a combination of air and road travel. There is scheduled air service from Quito to Cuenca and Loja, the cities northwest and southwest of the property. From these centers, small aircraft can be chartered to fly to Gualaquiza, the nearest airfield to the deposit.

There is road access from Quito to Cuenca for the transport of samples or heavy equipment. From Cuenca, a system of paved and gravel roads leads to the village of Tundayme, 6 km from the project site. The road distance is approximately 230 km and the travel time is about five to six hours. There is also road access from Tundayme to the Pacific Ocean port of Machala.

Corriente reports that the initial engineering study has been performed on the main access road from Chuchumbletza to the Mirador site (approximately 17 km). The definitive road design will be completed on October 23, 2006. The study will turn into a road improvement bid package to upgrade the existing dirt road to a 7.2-meter wide access road from Chuchumbletza to the site. This road improvement is planned to begin before the end of 2006.

Corriente constructed a six-kilometer pilot road in 2005, which passes just south of the Mirador Norte deposit area and provides access to the east side of the Mirador deposit. Trails from various points along this road provide access to most of the critical sectors of the project area.

5.2     Climate

The area has a wet equatorial climate with a reported rainfall of 2,300 millimeters (mm) per year. Rainfall can exceed 60 mm in a 24-hour period. Variations in the local terrain exert a strong influence over rainfall, so the area has many different local rain regimes. Fieldwork is possible all year round. The best time for airborne surveys or road and trail construction is from October to December, because of clearer skies and drier weather conditions.

5.3     Physiography

Tributaries of the Rio Zamora drain the central and western parts of the Mirador property. The flanking highland areas of the Paramos de Matanga on the west, and the Cordillera de Condor on the east, rise to maximum elevations of 4,200 and 3,500 meters above sea level ("masl"), respectively. The elevations of the property range from about 800 to 1,400 masl. The property supports second-growth tropical forest, although there are numerous clearings at lower elevations.

5.4     Infrastructure

The Mirador exploration camp is supplied with electricity from the local power grid.

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The closest existing airstrip is at Gualaquiza, about 40 km to the northwest of the deposit. It has an asphalt runway approximately 2,075 m long (AMEC, 2004). The availability and sources of water, mining personnel, potential tailings storage areas, potential waste disposal areas and processing plant sites are discussed at length in the May 2005 Feasibility Study Report (AMEC, 2005).

In an internal memorandum dated October 6, 2006, Corriente's Ecuadorian subsidiary EcuaCorriente S.A. reported:

"We are currently evaluating several viable alternatives for the Mirador Project power supply. The estimated demand for the Mirador project is 30 MW. The options under consideration listed in order of priority include the following:

1.    Connect to an existing hydroelectric plant that is located near the Mirador project site. With planned expansions, this hydroelectric plant complex will have a capacity of 59 MW.

2.    Develop Santa Cruz (in-house project) – Potential 56 MW (preliminary evaluation) hydroelectric project located approximately 15 km from the Mirador project site.

3.    Develop Sabanilla – potential 30 MW hydroelectric projects located 70 km from the Mirador project site.

4.    Connect to the Ecuadorian electrical grid. We are considering two options for the connection. The first option is to build a transmission line from the Mirador site to Limon (approximately 65 km) and upgrade the existing transmission line between Limon and Cuenca (approximately 61 km). The second option is to build a transmission line from the Mirador site to the Molino substation at the Paute Hydroelectric plant (approximately 140 km) which is the strongest distribution point on the Ecuadorian power grid.

5.    Install onsite thermal power generation plant.

Note that options 1 through 4 would be connected to the Mirador site by dedicated power transmission lines to guarantee a dedicated power source for Mirador. The above options are being evaluated for economic feasibility, stability, reliability, constructability, and maintainability. We are confident that we can secure a reliable power supply for Mirador phase one and also for future expansion with several additional hydroelectric options near the Mirador site."

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6.0     HISTORY

6.1     Exploration History

Billiton Ecuador B.V., now BHP Billiton S.A. ("Billiton") began regional exploration in southeastern Ecuador in 1994. Stream-sediment sampling was the main tool used to locate base metal anomalies. After further follow-up and mapping, Billiton identified possible porphyry copper systems associated with these anomalies. At least eight separate porphyry copper systems have now been identified in the region (AMEC, 2004).

The area of the present Mirador property attracted interest during the original reconnaissance geological and geochemical surveys completed in December 1994. These surveys, which included the collection of 315 stream sediment pan concentrate samples, identified a 50 sq. km drainage area where stream sediments contained anomalous grades of Cu, Mo, Au, Zn, and Ag. During the period from 1995 to 1999, Billiton was forced to restrict its activities to the north part of the region, away from the Perúvian border. A large area in the Cordillera del Condor, including the Mirador property, was declared off limits by the Ecuadorian Government during the time of the border conflict between Ecuador and Perú.

After Ecuador and Perú signed a peace treaty in July 1999, Billiton completed detailed follow-up surveys to better define the anomalous areas at the Mirador property. Billiton collected 746 soil samples along ridges and 219 rock chips from outcrops in stream drainages traversing the anomalous zones. This work, along with geological mapping, defined the anomalous zone that later became the Mirador deposit. In April 2000, Billiton and Corriente entered into an agreement covering the area of the Mirador property.

In February 2002, after the completion of 52 diamond drill holes (Phases 1 and 2) at the Mirador deposit, Corriente published the results of a mineral resource estimate (Makepeace, February 2002). The estimated tonnage and grade, calculated at a 0.65% Cu cutoff grade, were 218 million tonnes grading 0.73% Cu, all in the Inferred Mineral Resource category.

In February 2003, Corriente published the results of another mineral resource estimate based on the 62 (Phases 1, 2 and 3) holes completed at the Mirador deposit (Dawson and Makepeace, 2003). The estimated tonnage and grade, calculated at a 0.65% Cu cutoff grade, were stated as 182 million tonnes grading 0.76% Cu, all in the Inferred Mineral Resource category. An average gold grade of 0.22 g/t was reported to accompany this copper resource.

In July 2003, Sumitomo of Japan completed independent metallurgical tests on mineralized material from the Mirador deposit, with favourable results. AMEC reviewed this work and found it to be done to industry standard. Subsequent follow-up work has confirmed its conclusions (AMEC, 2004). The metallurgy of the Mirador mineralization is discussed in more detail in Section 16 of this report.

A fourth phase of drilling was conducted at the Mirador deposit between December 2003 and April 2004. A total of 8,091 m of core drilling was completed in 29 holes.

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In November 2003, Corriente commissioned AMEC Americas Limited ("AMEC") to be the primary consultant for the preparation of a bankable feasibility study for the Mirador Copper Project. Knight Piésold Ltd was responsible for the design of a Tailings Management Facility and related infrastructure, and Merit Consultants International Inc. provided study coordination, project planning and scheduling and capital cost estimates. The Feasibility Study Report, which did not consider the Mirador Norte prospect, was completed in May 2005.

In 2004, Corriente engaged AMEC to provide a mineral resource estimate and Qualified Person's review and Technical Report for the Mirador Project. The work entailed estimating mineral resources for the Mirador deposit in conformance with the CIM Mineral Resource and Mineral Reserve definitions referred to in National Instrument ("NI") 43-101, Standards of Disclosure for Mineral Projects. It also involved the preparation of a Technical Report as defined in NI 43-101 and in compliance with the format set out in 43-101F1. That Technical Report, titled "Technical Report, Mirador Project, Morona Santiago (sic) Province, Ecuador" and dated October 22, 2004, was filed on SEDAR on October 22, 2004. Susan Lomas, P.Geo., an employee of AMEC, served as the Qualified Person responsible for preparing the resource estimate presented in the October 2004 AMEC report. This mineral resource estimate, based on data from the 91 core holes completed at the Mirador deposit as of April 2004, was also used in the preparation of the AMEC May 2005 Feasibility Study Report. The details of the mineral resource estimate are set out in this Feasibility Study Report, in the section titled "2004 Mineral Resource Estimate (AMEC)".

This historic Mirador deposit mineral resource estimate is superseded by a more recent estimate (MDA, 2005). Both mineral resource estimates were prepared in compliance with National Instrument 43-101 and CIM definitions, using 3-D geological modeling/mining software. Drilling at the Mirador project totals 36,284 m in 143 core holes.

Corriente conducted 11,935 m of core drilling at the Mirador deposit in 2005. Most of this 52-hole program involved the drilling of angled infill drill holes that were intended to better define the early porphyry dikes, which account for most of the lower-grade zones in the deposit, and the post-mineral dikes. A six-kilometer pilot road was pushed through to the east side of the deposit from the existing access road leading south from the camp, creating better access to the drill platforms.

In the fourth quarter of 2005, Corriente retained MDA to prepare an updated mineral resource estimate for the Mirador deposit and to conduct pit optimization studies. The purpose of the mineral resource estimate update was to incorporate the new data from the 52 new drill holes completed in the Mirador deposit in 2005 into the resource model. MDA relied upon the results of previous work, and, unless there were compelling reasons to do otherwise, used procedures similar to those used by AMEC in the preparation of the 2004 Mirador deposit mineral resource estimate (AMEC, 2004).

The Mirador Norte deposit was discovered by Corriente in March 2003, during geological mapping in the area surrounding the Mirador deposit. Gossanous leached outcrops were noted along the road leading to Valle de Quime village, and gossanous and quartz-sericite altered clasts were discovered in two creeks crossing the same road. Mapping traverses up a small tributary of the Rio Wawayme led to

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the discovery of disseminated chalcopyrite with patchy chalcocite in silicified granodiorite and porphyry. Semi-continuous rock chip sampling returned some values of over 1% copper, and a ridge soil-sample program was subsequently completed. This outlined a large, strong, copper-gold-molybdenum anomaly centered on a zone of strong zinc depletion that attracted interest because of its similarity to the geochemical 'signature' typical of the other porphyry deposits in the area. The first four drill holes were completed in July 2003, and these confirmed that porphyry copper mineralization was present.

Corriente completed 5,812.69 m of core drilling in 25 holes at Mirador Norte in 2004, and 39 holes totaling 6,780.57 m in 2006. The total core drilling to the date of the present report is 13,605.16 m in 68 holes.

In August 2006, Corriente asked MDA to prepare a mineral resource estimate and pit optimizations for the Mirador Norte deposit, in compliance with National Instrument 43-101 and CIM definitions. This is the first time that such work has been performed for the Mirador Norte deposit. MDA was also requested to prepare an updated NI 43-101 Technical Report for the Mirador Project, to include the new Mirador Norte resource. The updated Technical Report is in the format defined in National Instrument 43-101 and is in compliance with the format set out in NI 43-101F1.

6.2     2004 Mirador Deposit Mineral Resource Estimate (AMEC)

The mineral resource for the Mirador deposit was estimated under the direction of Susan Lomas, P.Geo., of AMEC. The estimate was made from a 3-dimensional block model utilizing commercial mine planning software (Gemcom®). Pertinent parts of the report titled "Technical Report, Mirador Project, Morona Santiago Province, Ecuador" (AMEC, 2004) are extracted verbatim.

Geologic models were created of the dikes and the supergene units. AMEC checked the shapes for interpretational consistency on section and plan, and found them to have been properly constructed. To constrain grade interpolation in each of the zones, AMEC created 3-dimensional mineralized envelopes based on copper and gold grades. These were derived by a method of Probability Assisted Constrained Kriging (PACK) to initially outline a general shape. The threshold grade for Au was 0.2 g/t and for Cu it was 0.5%.

The data analyses were conducted on original and 6 m composited assay data. AMEC reviewed the compositing process and found it to have been performed correctly. Detailed data analysis indicated the domaining and tagging of the assay and the composite data functioned well.

Extreme grades were examined for copper and gold composite values. Cu grades had a smooth distribution with few extreme grades. Gold showed extreme grade values and a grade cap of 0.60 g/t was imposed on the assay data prior to grade interpolation.

Variography was completed for gold and copper on composite data from the main mineralized unit within and outside the grade probability shells. Only hypogene material was investigated. The copper

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correlograms showed ENE-WSW trending, steeply dipping structures while the gold correlograms showed NS trending, subvertical structures.

Values for copper, capped and uncapped gold, and bulk density were interpolated into the block model using ordinary kriging (OK), inverse distance weighting to the eighth power (ID8) and the nearest-neighbour (NN) methods.

AMEC completed a review of the Mirador resource block model. The model was checked for proper coding of drill hole intervals and block model cells. Gold and copper grade interpolation was examined relative to drill hole composite values by inspecting the sections and plans. The checks showed good agreement between drill hole composite values and model cell values.

AMEC checked the block model estimates for global bias by comparing the average copper and gold grades from the model ID8 with means from OK and NN estimates. The results show no evidence of bias in the estimate.

AMEC checked for local trends in the grade estimates by plotting the results from the OK, ID, and NN estimate results on easting, northing and elevation swath plots. The results for copper and gold grade inside the grade probability shells show close tracking between the three estimates and no local trends.

The final check performed, was to check the model for smoothing through the Discrete Gaussian or Hermitian polynomial change-of-support method described by Journel and Huijbregts (Mining Geostatistics, Academic Press, 1978). The grade-tonnage predictions produced for the model show that grade and tonnage estimates are validated by the change-of-support calculations over the likely range of mining grade cutoff values (0.4% to 0.6% Cu).

The mineral resources of the Mirador project were classified by AMEC using logic consistent with the CIM definitions referred to in National Instrument 43-101. The project mineral resources were classified as either Indicated or Inferred Mineral Resources. Table 6.1 contains the results of the resource estimation for the Mirador Deposit as of 23 September 2004. The resource estimate result for Mirador was declared using the 0.40% Cu cutoff. The resources were reported to a depth of 850 m elevation, which was approximately 500 m below the surface.

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Table 6.1 Mirador Deposit Mineral Resource Summary – 23 September 2004

      Au Cu
 

Zone

 Tonnes (g/t) (%)
0.4 Cu % Cutoff      
Indicated Mineral Resource      
 

Mixed

 1,300,000 0.23 0.57
 

Enriched

 6,700,000 0.24 0.99
 

MNZD

 301,700,000 0.20 0.65
Totals

Indicated Hypogene

 301,700,000 0.20 0.65
 

Indicated Supergene

 8,000,000 0.24 0.92
Inferred Mineral Resource      
  Mixed      
  Enriched 1,200,000 0.25 0.83
  MNZD 313,900,000 0.17 0.56
Totals Inferred Hypogene 313,900,000 0.17 0.56
  Inferred Supergene 1,200,000 0.25 0.83
   
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7.0     GEOLOGICAL SETTING

7.1     Regional Geology

The copper-gold-silver mineralization of the Mirador and Mirador Norte deposits is hosted by Late Jurassic granite and porphyries of the Zamora Batholith. This batholith is one of a number of Jurassic intrusions in the Cordillera Real and sub-Andean regions of Ecuador that have been mapped as members of the Abitigua Subdivision. Isotopic age dates for the younger Late Jurassic porphyry intrusive phases of the Zamora Batholith range from 152 to 157 Ma.

To the south of the Mirador deposit, sandstone of the Cretaceous Hollin Formation forms 50-m to 80-m high cliffs. This resistant unit is the youngest in the area, and unconformably overlies the Jurassic intrusive rocks of the Zamora batholith and covers the southern limits of the alteration and mineralization of the Mirador deposit.

7.2     Local and Property Geology

The Zamora batholith forms the wall rocks of both the Mirador and Mirador Norte porphyry copper-gold systems. Within the mineralized zone of the Mirador deposit, the intrusion comprises mainly equigranular Zamora granite/granodiorite, with some minor leucogranite dikes along the west and southwest margins, and rare diabase dikes up to two meters in width. In drill core the Zamora granite appears highly fractured; this is a weathering effect and is due to the dissolution of anhydrite and gypsum from veinlets. Where anhydrite is unaltered by weathering and leaching, the drill core is relatively competent. A typical cross section of the Corriente Mirador deposit model that helps to illustrate the following geological discussion is presented in Figure 7.1.

The oldest porphyritic rocks that intrude Zamora granite within the limits of the Mirador deposit are trachytic hornblende-feldspar dikes ("Jefp"), which strike north and east. A dike in the southern part of the deposit appears to be slightly older than the northern dikes, based on its degree of mineralization. In highly altered zones and in leached surface exposures, the porphyritic dikes are distinguished from the Zamora granite mainly by their large hornblende phenocrysts and equant feldspar crystals.

Near the center of the mineralized system is a large vertical diatreme of breccia ("brmn", not shown in Figure 7.1 but parallels and is inside of the mineralized zone), composed of angular fragments of the early porphyry dikes, Zamora granite, and quartz-vein fragments. The early porphyry dikes can be traced into the breccia but the brecciation obscures the contacts between the granite and early porphyry. The breccia is mostly fragment-supported, and the matrix consists of rock flour and fine rock and vein fragments. The matrix also contains sulfide-filled vugs, which, together with the quartz-vein fragments, allow mapping of the unit in weathered surface exposures. Fragments are angular to sub-angular and show potassic alteration.

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Northeast-striking, northwest-dipping hornblende-feldspar porphyry dikes ("Jhbp") cut the breccia and the wall rocks of the deposit. Based on their degrees of alteration and mineralization, these dikes are believed to have relative emplacement ages ranging from syn-mineral to post-mineral. These dikes are larger and more numerous along the southeast and northwest margins of the mineralization. A quartz-rich variety appears to be the youngest in the series. These rocks are sparsely fractured relative to the mineralized rocks and lack any quartz veining or high-temperature alteration. Outcrops are blocky and resistant, and weather to a characteristic bright red clay due to the oxidation of abundant magnetite.

The youngest rocks are post-mineral hydrothermal breccia dikes and irregular diatremes ("brpm"). These intrusive breccias are characterized by a polymictic clast assemblage of mineralized and unmineralized rock, the relative quantity of each clast type being dependent on whether the breccia intruded mainly mineralized rocks, or post-mineral intrusions. The matrix is finely ground rock; in some places, the matrix also contains milled sulfide minerals. The breccia dikes and diatremes seem to have preferentially intruded post-mineral dikes. They are most common along the southeast margin of the deposit. Intrusive breccia also occurs as irregular plugs around the north and northeast margins of the mineralized zone. Copper grades within the intrusive breccia range from very low to slightly less than the deposit average, depending on the amount of mineralized rock incorporated. Outcrops of this breccia are massive and very sparsely fractured. In drill core, the breccia is the least fractured lithology in the deposit.

Both the Mirador and Mirador Norte porphyry systems exhibit typical porphyry alteration zoning, with cores of potassic alteration evidenced by pervasive fine-grained secondary biotite nuclei. Mirador is surrounded by a large (approximately four square kilometers) quartz-sericite-pyrite (phyllic) alteration zone. This phyllic alteration weakly overprints much of the potassic alteration in the core of the system. Propylitic alteration is the most distal evidence of both of the porphyry systems.

The geology of the Mirador Norte deposit is very similar to that of Mirador. The outer or peripheral alteration 'haloes' of the two deposits nearly coalesce, since the center-points of the deposits are only three kilometers apart and the alteration systems are each at least two kilometers in diameter. Mineralization at Mirador Norte is hosted by Zamora granodiorite and northwest-trending, hornblende-feldspar porphyry ("andesite porphyry") dikes; these are very similar to the dikes at the at the Mirador deposit. As at Mirador, the Mirador Norte granodiorite is equigranular and medium grained; biotite is the predominant mafic mineral. Granodiorite and andesite porphyry units are very difficult to tell apart in leached outcrops or trail cuts, and so surface mapping of them is limited to exposures along the creek draining the center of the deposit. The present geological model for the porphyry dikes is mostly based on interpretation from drill core. The interpreted northwest orientation of the andesite porphyry dikes fits the drill intersections well, and also matches the overall soil anomaly trend. The southern end of the deposit is covered by as much as 30 m of coarse gravel and sand alluvial deposits of the Rio Wawayme valley.

At Mirador Norte, the alteration is predominantly potassic, with moderate to strong secondary biotite replacing primary biotite and hornblende. This pervasive alteration is overprinted by chlorite in the central and eastern areas, and by intense argillic alteration in the enriched zone that decreases with depth, but persists along structures.

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Figure 7.2 Drill Core Photo of DDH M64 Showing Low RQD

Figure 7.3 Drill Core with Unaltered Anhydrite (Below the Gypsum Front)

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8.0     DEPOSIT TYPES

The host rock, alteration, and mineralization of the Mirador and Mirador Norte deposits are typical of calc-alkaline porphyry copper systems. Copper deposits of a similar style are widespread in the Cordilleras of North and South America.

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9.0     MINERALIZATION

The sequence of mineral deposition in the Mirador deposit has been divided into early-stage molybdenum, early-stage copper ± gold, and late-stage copper + gold events, with a final weak polymetallic vein stage. Both copper-gold depositional events are dominated by chalcopyrite, with traces of native gold.

Molybdenite is present in systems of early-stage quartz veins that have a preferred east-west orientation. These veins occur as stockwork in both Zamora granite and early porphyry dikes.

Early copper-gold mineralization at the Mirador deposit occurs as finely disseminated chalcopyrite (with traces of native gold), associated with pervasive potassic alteration (mainly as secondary biotite). The later copper-gold event postdates the emplacement of the central breccia diatreme. This mineralization is characterized by abundant disseminated chalcopyrite in texture-destructive potassic alteration zones in the granite and early porphyry, and as coarse disseminations and centimeter-size intra-clast blebs in the central diatreme breccia. Mineralization is generally less abundant in the early porphyry dikes because either they were not as receptive to mineralizing fluids as the granite, or they were emplaced slightly after the peak of the early copper-gold mineralization phase. However, the southernmost early porphyry dike is just as strongly mineralized as the Zamora granite.

A third and minor mineralized event is manifested by subvertical, widespread, sparsely distributed polymetallic sulfide veins that are less than five centimeters in width. The veins include several varieties, ranging from massive pyrite veins with elevated gold grades to massive chalcopyrite-pyrite-sphalerite veins with elevated silver, zinc, copper and gold grades. These veins cut the youngest of the late-stage porphyry dikes, as well as all other rock types.

At both Mirador and Mirador Norte, the porphyry, granite, and breccia were impregnated with anhydrite veins and blebs during the potassic alteration and chalcopyrite-mineralizing phase. Meteoric fluids percolated down from the surface and hydrated the anhydrite, converting it to gypsum. This process, with the accompanying ~50% volume increase, shattered the host rock and filled the fractures with gypsum. Once the deposit was exposed by erosion, meteoric water filtered down and leached gypsum from the rock leaving weakly cemented or open fractures. The zone of poor rock quality migrated downward in the deposit area as a relatively flat hydration front. Below the hydration front, the mineralized rocks are less fractured and the anhydrite fracture filling is unaltered.

At Mirador Norte, there is a leached zone ranging from zero meters thick in the main creek valley to 40 meters thick under the main ridges. The leached zone overlies a secondary enrichment blanket averaging 14 meters thick that is characterized by chalcocite coatings on chalcopyrite and pyrite. In many holes the transition from leached to enriched is marked by centimeter to meter-size remnant zones of sulfides in the leached zone; this material has been separately mapped as a "mixed" zone. The enriched zone grades into primary disseminated chalcopyrite mineralization. Higher-grade areas are associated with structurally controlled, fine-grained, dark gray silica flooding, which can contain more than 5% chalcopyrite in two-meter drill-core intervals. These silica-flooded zones have diffuse margins. Barren early quartz-vein stockwork is most intense at the northern end of the deposit. Copper grades are

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similar in both granodiorite and porphyry, although at the south margin of the deposit the copper grades in porphyry show some variation. In drill-holes MN16, MN58, and MN59 the copper grade is slightly lower in the porphyry than in the granodiorite, but in drill-hole MN18 the copper grade increases in the porphyry (Drobe, 2006).

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10.0     EXPLORATION

The first exploration in the area of the present Mirador property was conducted by Billiton. The area attracted Billiton's interest during the original reconnaissance geological and geochemical surveys completed in December 1994. These surveys, which included the collection of 315 stream sediment pan concentrate samples, identified a drainage area of roughly 50 sq km that contained anomalous grades of Cu, Mo, Au, Zn, and Ag. There was an exploration hiatus from 1995 to 1999, when the area of the present property was declared off limits by the Ecuadorian Government because of the border conflict between Ecuador and Perú.

After the peace treaty of July 1999, Billiton completed detailed follow-up surveys to better define the anomalous areas of the Mirador property. The company collected 746 soil samples along ridges and 219 rock chips from outcrops in stream drainages traversing the anomalous zones. This work, along with geological mapping, defined the anomalous geochemical 'signature' of the main Mirador deposit. In April 2000, Billiton and Corriente entered into an agreement covering the area of the Mirador property.

Since April 2000, Corriente has conducted all of the exploration work on the Mirador property. The work has included geological mapping, pan concentrate sampling of stream sediments, soil geochemical sampling, rock chip sampling and the completion of 36,284 m of core drilling in 143 diamond drill holes at the Mirador deposit and 13, 605 m of core drilling in 68 holes at Mirador Norte. The Mirador deposit drill holes are consecutively numbered from M1 to M141, but there are two sets of holes with the same collar number (M74 and M74A, and M139 and M139A). As a result, in spite of the fact that the drill hole numbering sequence ends at M141, there were 143 holes drilled in the Mirador deposit to the end of 2005. The total number of drill holes for both deposits is 211; their aggregate length is 49,889 m. A summary of the drilling done at Mirador and Mirador Norte is presented in Table 10.1.

Table 10.1 Statistics and History of Mirador and Mirador Norte Drilling Programs
(Source: Corriente Resources Inc)

Deposit Year Hole Sequence Number of Holes Total Length
Mirador 2000 M01 – M32 32 5654.17
Mirador 2001 M33 – M52 20 7864.55
Mirador 2002 M53 – M62 10 2738.75
Mirador Norte 2003 MN01 – MN04 4 1011.9
Mirador 2003 - 2004 M63 – M90 29* 8091.62
Mirador Norte 2004 MN05 – MN29 26* 5812.69
Mirador 2005 M91 – M141 52* 11935.11
Mirador Norte 2006 MN30 – MN68 39 6780.57
         
Mirador All Years M01 – M141 143 36,284.2 m
Mirador Norte All Years MN01 – MN68 69* 13,605.16 m

* There are three sets of holes with the same collar number, M74/ M74A and M139/M139A and MN25/MN25A.

   
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10.1     2000

In May 2000, the first phase of drilling at Mirador began, under the supervision of J. David Lowell, who was under contract to Corriente. A total of 5,383 m of drilling was completed in 30 core holes in the Mirador deposit (M1 to M30).

10.2     2001

Between January and May of 2001, the second phase of drilling in the Mirador deposit was carried out. Twenty-two core holes (M31 to M52) were completed, with an aggregate length of 8,136 m.

10.3     2002

The third phase of drilling was conducted between February and April of 2002, and 10 core holes (M53 to M62) were drilled in the Mirador deposit, totalling 2,739 m. In October 2002, Corriente assumed the management of all aspects of the project.

10.4     2003

In February 2003 a study of the Mirador deposit was completed and was filed as a Technical Report entitled "Mirador Project, Corriente Copper Belt, Southeast Ecuador, Order of Magnitude Study, Part 1, Technical Report". The Technical Report included a polygonal mineral resource estimate based on the 62 drill holes completed at the Mirador deposit between 2000 and 2002. Both the Technical Report and the mineral resource estimate were completed under the supervision of Qualified Persons James M. Dawson, P.Eng. and David K. Makepeace, P.Eng. (Dawson and Makepeace, 2003).

In July, Sumitomo of Japan completed independent metallurgical tests showing favourable concentrate potential. AMEC reviewed this work and found it to be done to industry standard, and subsequent follow-up work has confirmed AMEC's conclusions. Metallurgy is discussed in detail in Section 16 of this report.

The Mirador Norte deposit was discovered in March 2003. Four core holes (MN01 to MN04) tested the new discovery; their aggregate length was 1,012 m.

10.5     2004

A fourth phase of drilling was conducted at the Mirador deposit between December 2003 and April 2004. A total of 8,091 m of core drilling was completed in 29 holes (M63 to M90, including M74 and M74A). Exploration drilling continued at Mirador Norte, totalling 5,813 m of core drilling in 25 holes.

10.6     2005

Corriente focused exclusively on the Mirador deposit in 2005, and completed 11,935 m of core drilling in 52 holes (M91 to M141, including M139 and M139A). Much of this program involved the drilling of

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angled infill drill holes that were intended to better define the early porphyry dikes, which account for most of the lower-grade zones in the deposit. The data from the holes that intersected the dikes, together with new information from outcrops exposed during the construction of new drill trails, helped to confirm and refine contacts of known early porphyry dikes, particularly in the northern sector. A few holes targeted the late breccia dikes in the north part of the deposit, to better locate and define the dike contacts and to explore for potentially economic copper mineralization along the dike margins. The 2005 holes did not intersect any significant new dikes or any new areas of mineralization.

In addition to the drilling at the Mirador deposit, geological mapping of new drill trail exposures continued, and outcrops exposed in stream channels were re-mapped. A six-kilometer pilot road was constructed to the east side of the deposit from the existing access road leading south from the camp. This created large new exposures of mostly weathered and leached rock. These exposures were geologically mapped, and the new data were added to the geological database. The new geological information required only minor changes to be made to the existing maps; two dikes proved to project farther east than previously interpreted. Re-mapping of outcrops in stream channels north and west of the deposit was completed, allowing more accurate control of contact locations and increased understanding of alteration styles there. A geotechnical-oriented re-mapping of fractures and other geologic structures was also completed late in 2005. Over 1,200 measurements were collected in order to complement the oriented core structural data collected in the majority of the last 40 holes drilled. These data were submitted to Piteau Associates for incorporation into the geotechnical database for pit-slope stability studies.

10.7     2006

In 2006, Mirador Project exploration drilling focused on the Mirador Norte deposit. A total of 6,781 m of core drilling was completed in 39 holes, bringing the overall Mirador Norte total to 13,605 m of core drilling in 68 holes. No exploration work was done at the Mirador deposit itself in 2006, although some geological mapping of the limits of the Hollin Formation cover rocks was completed. SNC-Lavalin is leading ongoing engineering and construction work, as well as socio-economic and environmental studies that will culminate in the preparation of a bankable Feasibility Study for the Mirador Project.

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11.0     DRILLING

The Mirador deposit has been tested by 143 diamond drill holes totalling 36,284 m, arranged in a rough grid on approximately 75-m to 100-m centers. The Mirador Norte deposit total is 13,605 m of core drilling in 68 holes, arranged on a similar grid. The total exploration and geotechnical drilling for both deposits stands at 49,889 m in 211 core holes. The drill-hole information has been tabulated in Appendix B and the collar locations are shown in Figure 11.1 for Mirador and in Figure 11.2 for Mirador Norte.

MDA walked the surface of Mirador Norte taking GPS readings on drill-hole collars. The drill-hole collars GPS checks are given in Table 11.1. Twelve holes were surveyed, but four others could not be surveyed because vegetation hindered the GPS readings. Several other drill holes were seen but not surveyed. None of the check GPS readings verified the accuracy and precision of the drill-hole surveys but they did demonstrate reasonableness with respect to general location. The discrepancies in coordinates between the MDA ("GPS") check of Corriente's data ("Database") in the database is likely due to Corriente having used a more accurate and precise differential GPS, while MDA used only a handheld GPS. The less precise handheld GPS recorded a range of estimated location uncertainty of +/-13 m on average but as low as 8 m and as high as 22 m.

Table 11.1 List of Drill Holes Surveyed in Field – Mirador Norte

  GPS Database   Difference  
Hole name North East Elev. North East Elev. North East Elev.
MN02 9,606,832 783,470 941 9,606,811 783,458 932 -21 -12 -9
MN09 9,606,882 783,174 999 9,606,874 783,172 984 -8 -2 -15
MN15 9,606,618 783,409 911 9,606,601 783,402 894 -17 -7 -17
MN19 9,606,680 783,676 948 9,606,673 783,678 927 -7 2 -21
MN53 9,607,046 783,173 996 9,607,001 783,157 1,006 -45 -16 10
MN57 9,606,662 783,453 904 9,606,637 783,437 900 -25 -16 -4
MN59 9,606,604 783,271 NA 9,606,599 783,243 903 -5 -28 NA
MN61 9,606,578 783,699 948 9,606,558 783,691 934 -20 -8 -14
MN63 9,606,438 783,555 899 9,606,416 783,545 909 -22 -10 10
MN62 9,606,504 783,643 912 9,606,486 783,630 915 -18 -13 3
MN66 9,606,732 783,622 945 9,606,716 783,619 926 -16 -3 -19
MN67 9,606,360 783,491 900 9,606,345 783,479 902 -15 -12 2

Diamond drills belonging to the contractor Kluane International Drilling Inc. ("Kluane") of Canada were used to complete all the diamond-drilling programs on both deposits. Kluane used a man-portable wire-line drill, and all platforms were accessed via hand-built trails. Until 2005, there was no road access to the drill pads at the Mirador deposit, and access was gained by walking 1,500 m along a trail from the road. Now, a rough access road leads through the southern periphery of the Mirador Norte drill area and onwards into the east section of the Mirador drill area. Trails from various points along this road provide access to drill platforms at both exploration sites.

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Figure 11.1 Mirador Drill Hole Location Plan

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Figure 11.2 Mirador Norte Drill Hole Location Plan

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In all drill programs, drill core was recovered in standard NTW (5.7 cm) and BTW (4.2 cm) core tubes. The smaller BTW core was recovered from the lower parts of the deeper drill holes, after the rod string was changed to BTW diameter. Standard HQ size core (6.35 cm) was taken from a few of the geotechnical holes at the Mirador deposit. No geotechnical drilling has been done at Mirador Norte.

Because of the almost total lack of outcropping rock, very little was known of the geology of the Mirador deposit before the drilling campaigns began. Therefore, since the presence and orientation of any possible steeply dipping features could not be predicted, most of the early drill holes at Mirador were drilled vertically. As the geological knowledge of the deposit increased, it was recognized that there exist various geologic features with sub-vertical geometry, such as syn-mineral to post-mineral dikes and late-stage quartz-sulfide veinlets. Accordingly, in the 2004 and 2005 drilling programs, a greater percentage of holes with angles of -60° to -80° were drilled to help define such features.

Using a selected set of data, MDA compared grades, core recovery and Rock Quality Designation ("RQD") between angled and vertical holes in the Mirador deposit. In order to compare "apples to apples", the samples selected were only from within the central mineralized breccia. This restricted the comparison to similar rock types and styles of mineralization and limited the comparison spatially. Working within these constraints, a fair comparison could be made of the grades in vertical and angled holes. It is interesting to note that for all metals except zinc, the median and mean grades are higher in the vertical holes. There is a difference in grades between angle and vertical holes:

The core drilling data is systemically biased in that the angle holes were all directed to cross the lesser mineralized Jefp dikes or areas of breccia with suspected concentrations of Jefp fragments. If this the case, then the vertical holes will under-report the unmineralized or weakly mineralized dikes thereby mis-representing the full spectrum of mineralization and rock types. This analysis should continue to investigate fully the reason for these phenomena and their potential impact on grades used to estimate the resource. However, it can be said that there is a bias between angle and vertical holes in the central mineralized hydrothermal breccia and the bias and grade distortions are different for each metal.

The following field procedures were used in all of the Corriente drilling campaigns:

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boxes and converted the drill hole depth markers from feet to meters. The core boxes were then placed on a stand and photographed in natural light.

Fifty of the one hundred and forty two drill holes had no down-hole surveys. Of the remainder, twenty holes in the second and third phases of drilling were surveyed using a Tropari instrument, and the holes drilled in 2004 and 2005 were surveyed using a Sperry-Sun instrument. Five of the unsurveyed drill holes were drilled at angles between -60° and -70° (M01, M25, M25, M39, and M62). These holes were drilled on the periphery of the deposit.

After the drill holes were completed, the collar locations were marked with a large PVC pipe capped with a plastic cover (Figure 11.3).

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Figure 11.3 Drill-hole Collar Marker

Core recovery is good for this type of deposit, and averages about 91% overall for Mirador and 91% for Mirador Norte. In the zones of hypogene mineralization, recovery is 95% and 93% for Mirador and Mirador Norte, respectively, but relatively low core recovery is common in the leached rock near the surface in both deposits. The RQD measurements indicate that the rock quality is very low through much of the deposit; the average of all RQD measurements is 38% for Mirador (pers. comm., John Drobe, Corriente). At Mirador Norte, the RQD is 10%. Largely, the poor RQD is the result of the rock literally falling apart after the hydration of veinlet-hosted anhydrite to gypsum and the subsequent solution of the gypsum by groundwater.

For insight into geotechnical information with respect to rock type, the median, mean and CV (coefficient of variation or standard deviation / mean) are given in Figure 11.4, Figure 11.5, Figure 11.6, and Figure 11.7.

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Figure 11.4 Core Recovery Statistics by Material Type - Mirador

Note: median and mean are read on the left axis; CV on the right axis

Figure 11.5 RQD Recovery Statistics by Material Type - Mirador

Note: median and mean are read on the left axis; CV on the right axis

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Figure 11.6 Core Recovery Statistics by Material Type – Mirador Norte

Note: median and mean are read on the left axis; CV on the right axis

Figure 11.7 RQD Recovery Statistics by Material Type – Mirador Norte

Note: median and mean are read on the left axis; CV on the right axis

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Specific gravity measurements were made on pieces of core that weighed from 10 grams to 30 grams each. The samples were collected at 40-m intervals. In the drill programs from 2000 to 2002, specific gravity was determined by the displacement method, where the sample was weighed dry, then immersed in water. The amount of water displaced by the sample was measured in order to determine its volume. The specific gravity was calculated by dividing the dry sample weight by the weight of the displaced water. This is not a very accurate method, since some water is lost because the sample always retains moisture, and it is difficult to measure the volume of the displaced water with much accuracy. For the 2004 drilling program, the procedure was changed to the immersion method, where the samples were suspended with thin nylon monofilament and weighed dry, then immersed in water and weighed wet. This is generally a more accurate method, although porous samples must be sealed with a waterproof coating. There are 2,186 specific gravity measurements in the present 2006 Mirador database and 539 in the Mirador Norte database, from which the resource presented in this document was estimated.

 
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12.0     SAMPLING METHOD AND APPROACH

The drill core was delivered by truck to the Mirador camp. Corriente staff then opened the boxes and converted the drill hole depth markers from feet to meters. The core boxes were then placed on a stand and photographed in natural light.

The core was marked at one-meter intervals by a geotechnician, who then measured the core recoveries and RQD. Technicians completed a preliminary drill log, wherein they recorded the core recovery, structural features, fracture density and orientation, and RQD.

Each one-meter interval of core was assigned a sample number. Based on the style of mineralization, the individual one-meter samples were physically combined into composite samples of different lengths. The entire lengths of all the drill holes were sampled in this manner. The categories of mineralization used and the corresponding composite sample lengths were as follows:

The use of non-random sample lengths in the database does introduce a certain degree of bias, but with compositing and length-weighting the effect is minimized or eliminated. The standard practice is to use the same sample length for all material.

The sample intervals were recorded and assigned sample numbers. The core was split longitudinally using a diamond saw (Figure 12.1). No line was marked on the core to guide the splitting process. In cases where the core fragments were too small to be sawn, core fragments representing one-half of the core volume were randomly picked out of the core boxes by hand.

Each core sample was placed in its own plastic bag, and each bag was weighed and marked with the sample number. For the first four phases of drilling at the Mirador deposit, and for the 2003-2004 drilling programs at Mirador Norte, the samples were sent to a preparation laboratory in Quito, Ecuador. During the 2005 and 2006 phases of drilling, Corriente used the Acme preparation laboratory in Cuenca, Ecuador. Upon arrival in Cuenca, the truck driver reported to the office manager at Corriente's offices. The truck then proceeded to the preparation laboratory, where the office manager prepared a list for the insertion of the duplicate and standard reference material (SRM) and QA/QC samples, and presented that list, and a sample shipment form, to the manager of the preparation facility. The lab manager confirmed the sample shipment and the work orders, and lab batch numbers were scanned and forwarded to Corriente via email. The sampling programs conducted between 2000 and 2005 were planned and executed in a satisfactory manner.

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Figure 12.1 Core Saw Facility

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13.0     SAMPLE PREPARATION, ANALYSES, AND SECURITY

13.1     Sample Preparation and Analyses 2000-2004

Sample pulps from all drilling programs, including those at Mirador and Mirador Norte, were prepared at ALS Chemex laboratories in Quito by laboratory personnel. Earlier samples were processed and analyzed by Bondar-Clegg, prior to the merging of Bondar-Clegg and Chemex. Both of these preparation laboratories were independent from Corriente and its Ecuadorian subsidiary companies. Except for copper and gold, which were treated in a consistent manner, other elements that were analyzed varied somewhat through the period 2000 to 2004.

For all drill phases from 2000 to 2004, the following procedures remained consistent. The whole sample was crushed to 75% passing –10 mesh, and then a one-kilogram sub-sample ("split") was pulverized to 95% passing –150 mesh. A 100 gram split ("pulp sample") was taken from the one-kilogram pulverized sample and shipped to the ALS Chemex laboratory in Vancouver, Canada. Here the pulp samples were fire assayed for gold with an atomic absorption finish (using a 30-gram aliquot), and were analyzed for copper and other elements using four-acid digestion/atomic absorption spectroscopy ("AAS") methods (AMEC, 2004).

For the phase one and phase two drilling programs at the Mirador deposit (2000 and 2001), the samples were assayed for gold using the fire assay technique with an AAS finish (FA-AAS), and analyzed for copper, silver, lead, molybdenum and zinc using four acid digestion followed by AAS.

Samples from the third drilling phase at Mirador (2002) were assayed for gold using the FA-AAS technique and analyzed for copper, molybdenum and zinc using four acid digestion followed by AAS.

Samples from the 2004 drilling phase at Mirador and the 2003-2004 drilling programs at Mirador Norte were assayed for gold by FA-AAS and analyzed for copper and molybdenum using four acid digestion and AAS. For the first four holes at Mirador Norte (2003), the drill-core samples were analyzed by ALS using the ALS Chemex procedure AA61, but procedure AA62 was adopted for the subsequent holes. According to the 2006 ALS Chemex Schedule of Services, both procedures are four-acid, "near total" digestion ICP-AA methods, but AA61 is optimized for low detection limits and is intended for geochemical exploration, while AA62 is optimized for accuracy and precision at high-concentration levels.

13.2     Sample Preparation and Analyses 2005-2006

The 2005 (Mirador) and 2006 (Mirador Norte) drill core samples were prepared at the Acme Analytical Labs ("Acme") preparation facility in Cuenca, Ecuador. The sample preparation procedures were the same as were used in 2000 to 2004 by Bondar-Clegg and ALS Chemex, except that final sample pulverization was to 85% passing -200 mesh. The -200-mesh 100-g split material (pulp sample) was shipped to the Acme lab in Vancouver, Canada, for final analysis.

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For the copper determination, one-half gram of material was digested using a four-acid solvent, followed by inductively coupled plasma/atomic emission spectrometric ("ICP-AES") analysis. Gold was determined by 30-gram fire-assay fusion followed by ICP-AES analysis. All sample preparation procedures are appropriate and well done, and the assays and analyses are of good quality.

13.3     Sample Security

In all phases of drilling at Mirador and Mirador Norte, drill core samples remained under the control of authorized Corriente personnel from the time they left the drill platforms until they were delivered to the preparation laboratory. For shipment, the individual sample bags were put into woven polypropylene bags. Each of these bags was marked with the project number, the drill-hole number and a number identifying its place in the sequence of bags in the sample shipment. The shipment bags were secured with tape and rope, and were sent to the preparation laboratory in a contracted vehicle. In 2005, the practice of marking the shipment bags with the drill hole number was discontinued, and shipment bags were secured by number-coded nylon "zip" ties before shipment.

In the opinion of MDA and Sivertz, the sample security measures taken by Corriente were satisfactory.

 
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14.0     DATA VERIFICATION

14.1     Introduction

Data and interpretations from AMEC (2004) had been reported in previous 43-101 reports but have been left out for brevity. Those sections on pre-2005 work can be reviewed in previous 43-101 reports.

14.2     Quality Assurance/Quality Control Programs, Mirador 2005 and Mirador Norte 2003-2006

14.2.1  Summary and Conclusions

The 2005 fifth phase drilling program at the Mirador deposit included drill holes M91 through M141. The updated drill hole assay database contains 3,592 new assayed intervals from these holes. For the 2005 drilling program, Corriente generally followed the Quality Assurance/Quality Control (QA/QC) guidelines recommended by AMEC Americas Ltd (AMEC, 2004). MDA reviewed the results of the 2005 Corriente QA/QC program but did not take independent samples from the 2005 drill holes. MDA did take independent samples from prior drilling campaigns.

The discussion in the following paragraph relates to the 2005 Mirador deposit program only.

The sample preparation procedures are appropriate and well done, and the assays and analyses are of good quality. Based on the results of the assays and analyses of standard samples inserted into the sample stream, there does not appear to be any significant bias in the assay or analytical data. The results from the inserted blank samples indicate that the sample preparation procedures are conducted with appropriate care. Copper analyses of pulp duplicates reproduce well, while gold fire assays of pulp duplicates show modest variability. Although MDA does not believe that the modest variability in the reproducibility of gold assays has instilled any material bias or skewed the results, it is suggested that this phenomenon be investigated with a set of metallic screen samples. MDA and Sivertz also agree that a small percentage of samples should be sent "blind" to a second umpire laboratory, as a check on the primary laboratory.

For the 2006 Mirador Norte deposit drill program, the QA/QC procedures in place were very good but did leave two issues untested. One is the in-lab contamination and the second is the second lab check; the latter is partially but not completely assessed by the insertion of standards. The QA/QC procedures in place have demonstrated that the analyses could be used for confident resource estimation, albeit that inference is needed in some cases, subject to the statement in the previous paragraph.

Corriente found an analytical bias beginning during the last drill campaign, where copper standard grades decreased over time. Oddly, this bias was present in the analyses from one standard (MS2) but was not clearly present in the other (MS1). In both cases, the grades remained within the limits of two standard deviations from the mean. Corriente believes that this may have been caused by accumulation of moisture in one set of pulp standards. This standard insertion program also found several "busts" in

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sample batches, which were later corrected. It is clear that in almost all cases, the final batches of assays did pass the standard test for both copper and gold for both standards.

14.2.2  Sample Preparation and Analysis

Samples for the 2005 (fifth phase) drilling program at the Mirador deposit, and for the 2006 drilling program at Mirador Norte, were prepared and analyzed by the following procedures (paraphrased from John Drobe, 2005, personal communication):

The core was split by sawing or manual splitting and one-half of the core was used for sample analyses. The sampled intervals varied from 2 m to 5 m, depending upon the rock and style of mineralization, and so the samples typically weighed between 4 kg and 10 kg each. The samples were sent to the Acme sample preparation lab in Cuenca, Ecuador.

At the preparation lab, the samples were crushed to 70% passing 10 mesh. A split weighing one kilogram was taken from the crushed material for further processing, and the remainder was stored. As well, for every 1 in 20 samples, a second one-kilogram split was taken. This type of QA/QC sample is referred to as a "coarse-reject duplicate".

The minus 10-mesh one-kilogram split material was pulverized to 85% passing 200 mesh. A split weighing 100 g was taken from the pulverized material for assaying, and the rest was stored. In addition, for every one in 20 samples, a second 100-g split was taken. This type of QA/QC sample is referred to as a "pulp duplicate".

The coarse-reject duplicate material was inserted into the sample stream before pulverizing, and both the coarse-reject duplicate and pulp-duplicate samples were shipped with the regular samples. Approximately 2.5% of the final analyses (1 sample in 40) were of standard reference material ("SRM") MS1, while another 2.5% were of SRM MS2. The purpose of this insertion procedure is to ensure that the duplicate and SRM samples are received "blind", that is, it is intended and expected that the analytical laboratory receiving the pulp samples will not be able to distinguish the SRMs and duplicates from the rest of the shipped pulp samples.

The minus 200-mesh (pulp) 100-g split material was shipped to Acme Analytical Laboratories Ltd ("Acme") in Vancouver, Canada, for final analysis. For the copper determinations, one-half gram of material was digested using a four-acid solvent, followed by inductively coupled plasma - atomic emission spectroscopy (ICP-AES) analysis. Gold was determined by 30-gram fire-assay fusion followed by ICP-AES analysis.

The rule followed by Corriente was that if a SRM sample returned a value in either copper or gold that was outside of an acceptable range, then Acme would be requested to reanalyze 10 samples on either side of the SRM, or halfway between the next SRM in the sample stream that contained the questionable SRM result. The acceptable range was taken as the mean plus-or-minus two standard deviations. Lomas (2004) discusses in detail the procedure for preparing the SRMs and the testing by which the SRM statistics were determined.

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14.2.3   Duplicate Analyses on Pulps and Coarse Rejects – Mirador Deposit (2005)

The text, Tables, and Figures in the following section apply only to the 2005 QA/QC program for the Mirador deposit.

There are 183 copper and gold analytical results for duplicate-pulp samples, and 183 results for copper and gold on duplicate coarse-reject samples. These numbers represent about 5% of the total number of assay intervals in the Phase 5 (2005) Mirador deposit drill-hole database.

In general, there is good reproducibility for copper analyses between the original-sample grades and the duplicate-sample grades for both the pulp duplicates (Figure 14.1) and coarse-reject duplicates (Figure 14.3). The comparison between the original and the duplicate assays is not as good for gold as copper (Figure 14.2 and Figure 14.4; also note the R2 statistic in Table 14.1). Statistics for the original sample and duplicate assays, and the R2 value that measures the fit of the linear regression between the assay pairs are given in Table 14.1.

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Figure 14.1 Copper Duplicate Assays – Pulps

Figure 14.2 Gold Duplicate Assays – Pulps

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Figure 14.3 Copper Duplicate Assays – Coarse Rejects

Figure 14.4 Gold Duplicate Assays – Coarse Rejects

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Table 14.1 Statistics of the Duplicate Samples

 

 -200-mesh Pulp -200-mesh Pulp -10-mesh Coarse -10-mesh Coarse

Statistic

 Originals Duplicates Reject Originals Reject Duplicates

N Pairs

 183   183  

Minimum Cu (ppm)

 13 10 31 31

Maximum Cu (ppm)

 23,444 23,957 19,706 19,620

Mean Cu (ppm)

 4,901 4,900 4,575 4,577

Std Dev Cu (ppm)

 3,142 3,169 3,269 3,309

R2 Cu

 0.9984   0.9897  

Minimum Au (ppb)

 1 2 2 2

Maximum Au (ppb)

 642 729 1,567 1,433

Mean Au (ppb)

 166 168 179 176

Std Dev Au (ppb)

 112 114 151 145

R2 Au

 0.9325   0.9640  

In Figures 14.5 through 14.8, the relative differences between the original assays and the duplicate assays are plotted in sorted-order according to the average grade of the sample pairs. At the low end of the grade distribution, reproducibility is relatively poor for both copper (below ~300 ppm) and gold (below ~ 100 ppb). Note that there is a low bias in the duplicate in the low end of the population, which is rather unusual since the same laboratory was used to analyze both the original and the duplicate samples. This bias occurs for both copper and gold, and for both pulps and coarse-rejects. The bias is not particularly significant, because its magnitude is less than the average variation between the assay pairs, and because it only occurs in the low-grade samples.

Figures 14.9 through 14.12 present the absolute value of the relative differences between assay pairs and their mean grade. This better illustrates the slight increase in reproducibility with increasing grade, even in the high-grade part of the distribution. These graphs quantify the analytical reproducibility of the duplicate samples.

Table 14.2 presents the statistics for samples with >=1000 ppm Cu and >=125 ppb Au, here defined as "significantly mineralized". Ninety percent of these significantly mineralized sample pairs have a relative difference in copper grades of up to 4% for pulps and up to 6% for the coarse rejects. The 90th percentile for gold is 23% for pulp duplicates and 21% for coarse-reject duplicates.

Table 14.2 Absolute Value of the Relative Difference between Sample Pairs

 

 -200-mesh Pulp -10-mesh Coarse

 

 Duplicates Reject Duplicates

N Pairs for Cu>=1000 ppm

 164 153

50th percentile Cu

 1% 2%

90th percentile Cu

 4% 6%

95th percentile Cu

 5% 9%

N Pairs for Au>=125 ppb

 108 118

50th percentile Au

 4% 5%

90th percentile Au

 23% 21%

95th percentile Au

 39% 64%

 

Mine Development Associates  
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Figure 14.5 Relative Differences of Copper Duplicate Assays – Pulps

Figure 14.6 Relative Differences of Gold Duplicate Assays – Pulps

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Figure 14.7 Relative Differences of Copper Duplicate Assays – Coarse Rejects

Figure 14.8 Relative Differences of Gold Duplicate Assays – Coarse Rejects

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Figure 14.9 Absolute Value of the Relative Difference of Copper Duplicate Assays – Pulps

Figure 14.10 Absolute Value of the Relative Difference of Gold Duplicate Assays – Pulps

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Figure 14.11 Absolute Value of the Relative Difference of Copper Duplicate Assays – Coarse Rejects

Figure 14.12 Absolute Value of the Relative Difference of Gold Duplicate Assays – Coarse Rejects

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14.2.4   Duplicate Analyses on Pulps and Coarse Rejects – Mirador Norte

The text, Tables, and Figures in the following section apply to all of the QA/QC programs for the Mirador Norte deposit.

There are 214 copper and gold analytical results for duplicate-pulp samples, and 204 results for copper and gold on duplicate coarse-reject samples for the entire Mirador Norte database. These numbers represent about 5% and 4.8%, respectively, of the entire Mirador Norte sample set.

In general, there is no bias2 and there is good reproducibility for copper analyses between the original-sample grades and the duplicate-sample grades (pulp duplicates are shown in Figure 14.13 and Figure 14.14; coarse-reject duplicates are shown in Figure 14.15 and Figure 14.16). The comparison between the original and the duplicate assays is not as good for gold as for copper (Figure 14.17 through Figure 14.20). While the relative difference between the original-sample grades and the duplicate-sample grades ("reproducibility") for pulps for copper is around 2% and coarse reject copper reproducibility is approximately 8%, reproducibility for gold, at 16%, is much poorer. Molybdenum reproducibility is substantially worse than gold but since molybdenum is not being modeled, this is only a point of interest.

____________________
2 None is expected as the same lab is used for the original and the duplicate sample.

 

Mine Development Associates  
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Figure 14.13 Relative Difference of Copper Duplicate Assays – Pulps

Figure 14.14 Absolute Value of the Relative Difference of Copper Duplicate Assays – Pulps

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Figure 14.15 Relative Difference of Copper Duplicate Assays – Coarse Rejects

Figure 14.16 Absolute Value of the Relative Difference of Copper Duplicate Assays – Coarse Rejects

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Figure 14.17 Relative Difference of Gold Duplicate Assays – Pulps

Figure 14.18 Absolute Value of the Relative Difference of Gold Duplicate Assays – Pulps

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Figure 14.19 Relative Difference of Gold Duplicate Assays – Coarse Rejects

Figure 14.20 Absolute Value of the Relative Difference of Gold Duplicate Assays – Coarse Rejects

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14.2.5   Standard Reference Samples – Mirador Deposit

The text, Tables, and Figures in the following section apply only to the 2005 QA/QC program for the Mirador deposit.

Standard Reference Material (SRM) samples were inserted into the stream of pulps sent to Acme in Vancouver. MS1 is of medium grade and MS2 is low grade. Ninety-three samples of MS1 and 88 samples of MS2 were analyzed, representing 2.6% and 2.4% of the total number of assay intervals in the Phase 5 drill hole database, respectively.

The assay results for MS1 and MS2 are shown in Figures 14.21 to 14.24. The samples are plotted by the order of the sample numbers. Those points marked as original assays were those that "failed" and were re-analyzed.

The first 15 analyses on MS1 appear to cluster on the low side for copper, but there is no corresponding cluster for gold. There is no biased clustering for copper or gold for the MS2 samples. The lab reanalyzed thirteen batches that were deemed to have failed because they returned grades more than approximately two standard deviations from the mean SRM grade. Seven batches with failed copper and gold values were not requested to be re-analyzed, although the gold content of the SRM itself was sometimes re-analyzed. Some batches that had a failed SRM assay were not re-tested, because the batch contained only samples from unmineralized or weakly mineralized drill holes located outside of the deposit (John Drobe, 2005, personal communication). Of the batches that were re-analyzed, 12 of the SRMs were high in copper, one was low in copper, one was high in gold, and three were low in gold. Two batches that were re-analyzed returned out-of-range SRM values for the second time as well. Table 14.3 lists the batch failures.

Table 14.3 List of Re-Analyzed Batches – Mirador

 

 Batches Rerun   Batches Not Rerun

 

 MS1 MS2 MS1 MS2

High Cu

 5* 7 1 1

Low Cu

 0 1 1 0

High Au

 1 0 0 1

Low Au

 1 2 1 2

# Batches

 5 8 3 4

# Reruns w

 0 2 * *

bad SRM

        

*For one batch that was rerun, the high-Cu SRM was not rerun with the rest of the samples.

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Figure 14.21 Standard MS1 Checks – Copper - Mirador

Standard MS1 Analyses: Copper

Figure 14.22 Standard MS1 Checks – Gold - Mirador

Standard MS1 Analyses: Gold

 

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Figure 14.23 Standard MS2 Checks – Copper - Mirador

Standard MS2 Analyses: Copper

Figure 14.24 Standard MS2 Checks – Gold - Mirador

Standard M2 Analyses: Gold

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Descriptive statistics for the SRMs are given in Table 14.4. These statistics compare well with the parameters previously assigned to the SRMs, except that the copper for MS2 has some extreme outliers. Lomas (AMEC, 2004) discusses the testing from which the SRM statistics were determined.

Table 14.4 Descriptive Statistics of the Standard Reference Material

  -- MS1 --   -- MS2 --  
         
Statistic Phase 5 SRM Phase 5 SRM
  Analyses* Determinations Analyses* Determinations
N 93 41 88 40
Mean Cu 0.802 0.801 0.378 0.371
Std.Dev. Cu 0.024 0.018 0.028 0.010
CV Cu 0.03 0.02 0.07 0.02
Mean Au 0.285 0.287 0.162 0.163
Std.Dev. Au 0.018 0.021 0.015 0.011
CV Au 0.06 0.07 0.09 0.06
* The statistics are based on first-run analyses and exclude the rerun analyses.
note: CV = std dev / mean

14.2.6     Standard Reference Material – Mirador Norte Deposit

The text, Tables, and Figures in the following section apply to all the 2006 QA/QC programs for the Mirador Norte deposit.

Corriente continued to insert standard reference material into their sample stream when assaying Mirador Norte samples. When standards returned values greater or less than two standard deviations from the mean, the ten samples prior to and ten samples following the "failed" inserted standard, were rerun. The graphs shown in Figure 14.25 through Figure 14.28 show the results of those rerun and final batch samples.

 

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Figure 14.25 MS1 Round Robin and Sampling Results, Cu (%), (Mirador Norte)

Figure 14.26 MS1 Round Robin and Sampling Results, Au (ppm), (Mirador Norte)

 

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Figure 14.27 MS2 Round Robin and Sampling Results, Cu (%), (Mirador Norte)

Figure 14.28 MS2 Round Robin and Sampling Results, Au (ppm), (Mirador Norte)

 

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14.3     Mirador Norte Database Audit – 2006

Forty downhole surveys were re-read from the original photographs. In the forty original readings, one significant error was found, which was corrected. The entire Mirador Norte drill-hole database of gold and copper assays was audited against original (received from Corriente) assay lab reports. One error was found and it was not significant.

14.4     Sample Integrity

The Mirador deposits present a unique sampling situation. The distinctly low RQD material (Figure 11.5 and Figure 11.7) can make it difficult to obtain high core recovery, particularly in the leached rock near the surface in both deposits, and certain sections of highly fractured rock presents the opportunity to introduce sample bias. Because of this, two studies were conducted, one on the Mirador deposit (documented in an internal report), and one on Mirador Norte. The Mirador study demonstrated that in spite of the low RQD, the grade to core recovery relationship is due more to geology than to sampling bias; the same holds true for Mirador Norte. In spite of this, the work done in the Mirador Norte study is documented briefly below because it also provides insight into the style of mineralization.

The following discussion only considers samples with greater than 65% core recovery. Only 5% of all samples have recoveries of less than 65%; this is too small a number to be significant. The mean grade of samples steadily rises as core recovery decreases. Figure 14.29 shows this relationship very clearly. It also shows that sample grade increases as the number of fractures increases. While difficult to see at this scale, hardness and specific gravity decrease with increasing grade. Figure 14.30 shows that as RQD increases (left half of graph where there are sufficient samples), the grade decreases. It also shows that sample grade drops as the number of fractures drops (although this relationship reverses for the small population of samples with RQDs of over 50-55%).

There is a geological characteristic more important than just fracturing that relates the grade and rock quality; this is post-mineral, near-surface weathering. To test this, graphs were made of the same grades and rock characteristics against drill-hole depth and elevation (Figure 14.31 and Figure 14.32). It seems likely from these graphs that the grades were more affected by post-mineralization weathering than by fracturing thereby making the core recovery and grade relationship less critical. In Figure 14.32 it is strikingly obvious that copper and zinc are strongly leached near the surface, while molybdenum and gold are not, a fact that plays a significant role in how the resource estimate is made. Interestingly, there is a positive relationship between metal grades and number of horizontal fractures, but this is not so for metal grades and number of vertical fractures.

MDA concludes that the grade to RQD and core recovery relationship is a manifestation of geology and not indicative of sample bias.

 

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Figure 14.29 Core Recovery and Grades and Rock Characteristics (Mirador Norte)

Figure 14.30 RQD and Grades and Rock Characteristics (Mirador Norte)

 

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Figure 14.31 Hole Depth and Grades and Rock Characteristics (Mirador Norte)

Figure 14.32 Elevation and Grades and Rock Characteristics (Mirador Norte)

 

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14.5     Drill Site Field Checking

MDA walked the surface of Mirador Norte, taking GPS readings on drill-hole collars (Table 14.5) and also taking two samples (Table 14.6). Twelve holes were surveyed, but four others could not be surveyed because vegetation hindered the GPS readings. Several other drill holes were seen but not surveyed. None of the check GPS readings verified the accuracy and precision of the drill-hole surveys but they did demonstrate reasonableness with respect to general location. The discrepancies in coordinates between the MDA ("GPS") check of Corriente's data ("Database") in the database is likely due to Corriente having used a more accurate and precise differential GPS, while MDA used only a handheld GPS. The less precise handheld GPS recorded a range of estimated location uncertainty of +/-13 m on average but as low as 8 m and as high as 22 m.

Table 14.5 List of Drill Holes Surveyed in Field – Mirador Norte

 

GPS

Database

Difference

Hole name

North

East

Elev.

North

East

Elev.

North

East

Elev.

MN02

9,606,832

783,470

941

9,606,811

783,458

932

-21

-12

-9

MN09

9,606,882

783,174

999

9,606,874

783,172

984

-8

-2

-15

MN15

9,606,618

783,409

911

9,606,601

783,402

894

-17

-7

-17

MN19

9,606,680

783,676

948

9,606,673

783,678

927

-7

2

-21

MN53

9,607,046

783,173

996

9,607,001

783,157

1,006

-45

-16

10

MN57

9,606,662

783,453

904

9,606,637

783,437

900

-25

-16

-4

MN59

9,606,604

783,271

NA

9,606,599

783,243

903

-5

-28

NA

MN61

9,606,578

783,699

948

9,606,558

783,691

934

-20

-8

-14

MN63

9,606,438

783,555

899

9,606,416

783,545

909

-22

-10

10

MN62

9,606,504

783,643

912

9,606,486

783,630

915

-18

-13

3

MN66

9,606,732

783,622

945

9,606,716

783,619

926

-16

-3

-19

MN67

9,606,360

783,491

900

9,606,345

783,479

902

-15

-12

2

14.6     Mirador Norte MDA Check Samples

MDA took two surface samples and 17 split quarter-core samples for validation of the mineralization at Mirador Norte (Table 14.6). All samples were chosen by MDA and MDA was present during most of the core cutting. For periods of time MDA did leave the core cutting facility and the samples were not always under MDA's control. MDA cannot guarantee that the samples were not compromised but believes that there was neither reason, intent nor motivation to compromise the samples. The samples were bagged in plastic, closed with a plastic security strap, and then placed in rice bags with similar plastic security straps. The samples were kept at the unsecured core cutting area in the secured Mirador Camp. MDA did accompany the samples during transport and delivery to ACME Labs in Cuenca, Ecuador via the Panantza project exploration camp.

The check sample grades received from the laboratory were generally similar as expected, but the grades were, on average, slightly lower for copper and slightly higher for gold. The average difference in gold grades is considered negligible. The molybdenum grades were also lower, but at the very low grades of molybdenum reported, the difference is immaterial. The reason for the overall lower average copper grade in MDA's check samples should be determined for future work, but the corroboration of the metallurgical samples with original sample grades (see section 14.7) renders this difference less important. However, the discrepancy between the copper grades reported for the MDA check samples and the copper grades from the original Corriente core samples still should be investigated and addressed.

 

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Table 14.6 List of Independent Samples – Mirador Norte

Corriente

MDA

Difference (%)

Sample No.

Cu

Au

Mo

Zn

Sample No.

Cu

Au

Mo

Zn

Cu

Au

Mo

Zn

70621320330

2501

94

33

132

1

1871

39

33

170

-25%

-59%

2%

29%

70621350340

2826

55

4

23

2

2424

47

4

26

-14%

-15%

-17%

13%

7210660210

3900

50

10

NA

3

4885

63

9

46

25%

26%

-13%

 

7210690220

5600

92

10

NA

4

5118

86

8

38

-9%

-7%

-18%

 

7210720230

5800

142

10

NA

5

5967

119

8

30

3%

-16%

-17%

 

7210750240

8500

187

10

NA

6

9157

195

6

40

8%

4%

-45%

 

70341440480

5886

76

150

66

7

5466

69

103

60

-7%

-9%

-31%

-9%

70341460490

28085

532

110

131

8

22551

742

76

115

-20%

39%

-31%

-12%

70653010960

5663

73

20

48

9

5873

68

22

54

4%

-7%

9%

13%

70653040970

14407

176

15

128

10

13986

168

19

137

-3%

-5%

26%

7%

70653070980

7155

103

21

58

11

6108

81

20

51

-15%

-21%

-6%

-12%

7110740240

18800

24

80

NA

12

16657

34

50

28

-11%

42%

-38%

 

7150510170

25300

39

30

NA

13

17624

47

35

86

-30%

21%

15%

 

7250710110

7700

50

10

NA

14

7341

51

11

7

-5%

2%

11%

 

7041720430

3470

96

105

14

15

3190

98

53

9

-8%

2%

-50%

-36%

7041750440

4940

182

51

24

16

4358

174

21

18

-12%

-4%

-60%

-25%

7041780450

3990

125

200

23

17

3729

128

291

12

-7%

2%

45%

-48%

Mean

9090

123

51

65

 

8018

130

45

55

-12%

5%

-12%

-16%

Weighted Mean

 

 

 

 

 

 

 

 

 

-10%

2%

-10%

2%
                         

surface rock chip

 

 

 

18

4941

153

113

72

 

 

 

 

surface rock chip

 

 

 

19

3701

149

13.4

52

 

 

 

 

The two surface samples taken by MDA demonstrated mineralization at the site.

14.7     Mirador Norte Metallurgical Composite Sample Comparison

The grades of the composited metallurgical samples were compared to the original drill sample grades. Table 14.7 shows the results of this comparison and overall the composite metallurgical sample grade is 4% lower for copper and 12% higher for gold than the corresponding drill sample grades. Graphs of these data are given in Figure 14.33 and Figure 14.34. MDA considers this a good corroboration of the drill sample grades.

Table 14.7 Comparison of Metallurgical Sample and Drill Sample Grades (Mirador Norte)

Sample No.

G&T

Corriente

 

 

 

Head 1

Head 2

Head Avg

Sample

Drill samples

 

 

 

Cu

Au

Cu

Au

Cu

Au

Weight

Cu

Au

Zone

Description

 

(%)

(ppm)

(%)

(ppm)

(%)

(ppm)

(kg)

(%)

(ppm)

 

 

1

1.37

0.14

1.33

0.15

1.35

0.15

8.29

1.23

0.11

enriched

2normal+1mixed

2

0.42

0.11

0.41

0.1

0.42

0.11

46.00

0.39

0.08

primary

low

3

0.44

0.18

0.47

0.16

0.46

0.17

39.48

0.47

0.15

primary

dike

4

0.50

0.15

0.56

0.15

0.53

0.15

39.48

0.54

0.13

primary

dike

5

1.25

0.15

1.31

0.16

1.28

0.16

8.69

1.48

0.16

enriched

normal

6

0.37

0.06

0.44

0.06

0.41

0.06

56.09

0.43

0.06

primary

low

7

0.56

0.12

0.57

0.15

0.57

0.14

60.48

0.56

0.12

primary

dike

8

0.42

0.09

0.45

0.1

0.44

0.10

55.68

0.44

0.09

primary

low

9

0.51

0.17

0.58

0.15

0.55

0.16

50.95

0.57

0.15

primary

avg

10

0.44

0.08

0.48

0.12

0.46

0.10

79.34

0.48

0.08

primary

dike

11

0.51

0.11

0.55

0.1

0.53

0.11

81.33

0.56

0.11

primary

avg

12

0.63

0.09

0.63

0.08

0.63

0.09

44.68

0.62

0.07

primary

avg

13

1.02

0.06

1.03

0.08

1.03

0.07

10.74

1.06

0.06

enriched

2normal+1mixed

14

1.12

0.07

1.12

0.11

1.12

0.09

8.92

1.19

0.08

enriched

normal

15

0.98

0.06

0.96

0.1

0.97

0.08

12.72

1.20

0.07

enriched

normal

Mean

0.53

0.11

0.56

0.12

0.55

0.11

602.87

0.57

0.10

 

 

Difference

-7%

9%

-1%

14%

-4%

12%

 

 

 

 

 

 

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Figure 14.33 Metallurgical Sample Grade Comparison: Copper (Mirador Norte)

Figure 14.34 Metallurgical Sample Grade Comparison: Gold (Mirador Norte)

 

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15.0     ADJACENT PROPERTIES

Other than the mineral prospects and exploration activities of Corriente itself, there are no known mineral deposits or advanced mineral exploration projects immediately adjacent to the Mirador property. Aurelian Resources Inc. ("Aurelian"), a publicly owned Canadian mineral exploration company, has acquired mineral concessions adjacent to the Mirador property. According to information posted on the Aurelian website, these are part of a large group of concessions that Aurelian has been exploring for precious and base metals (www.aurelian.ca). In April 2006, Aurelian announced that it had intersected significant gold grades in two of its initial drill holes at the Fruta Del Norte epithermal gold prospect, located approximately 22 km south-southwest of the Mirador property. According to information posted on the Aurelian website, subsequent drilling to September 2006 has continued to intersect epithermal gold mineralization. In a July 2006 report prepared for Aurelian, and posted on the Aurelian website, author Richard H. Sillitoe states that "On the basis of the preliminary drilling completed to date, it is already apparent that Fruta Del Norte is a major, high-grade epithermal gold system".

 

 

 

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16.0     MINERAL PROCESSING AND METALLURGICAL TESTING

16.1     Introduction: Mirador Deposit

The following section is reproduced verbatim from the report titled "Mirador Copper Project Feasibility Study Report" (AMEC, 2005). There are formatting changes and the figure, table and appendix numbering is different. The present authors' comments or changes are placed in the body of AMEC's text in square brackets ([ ]) and are not italicized.

16.2     History of Mirador Deposit Metallurgical Testwork

A significant amount of metallurgical testwork has been undertaken on mineralized samples from the Mirador deposit since 2001. SGS Lakefield Research (Lakefield), in Lakefield, Ontario, Canada, carried out the main program of feasibility testing between December 2003 and September 2004. The groups responsible historically for the metallurgical testing aspects of the project are summarized below:

 

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In 2001 Geomet S.A. conducted a scoping rougher flotation test, on behalf of Billiton Chile, on an unidentified sample (Muestra 2) from Mirador.

In April 2002, Resource Development Inc. (RDI) conducted three batch rougher flotation tests also on unidentified samples.

In June 2003, Sumitomo Metal Mining Co., Ltd. (Sumitomo) conducted an independent scoping level metallurgical program on five selected drill core samples. This testing included batch rougher and cleaner flotation, mineralogical and chemical analysis of concentrates, and a bond work index determination. The liberation characteristics of the ore were also investigated. AMEC reviewed this work and found it to be done to industry standard.

Overall, the results of the Geomet, RDI and Sumitomo testwork showed the samples tested had relatively simple metallurgy and favourable commercial concentration potential. The subsequent follow-up feasibility work by Lakefield on 3,000 kg of split diamond drill core from 18 drill holes across the ore body, and at various depths, has confirmed their conclusions.

The feasibility metallurgical testwork carried out by Lakefield was done under the direction of AMEC. Lakefield also provided samples to MinnovEX and G&T Metallurgical Services (G&T) to conduct SPI grindability testwork, and mineralogical and flotation quality control testwork respectively. Lakefield and MinnovEX also conducted grinding circuit evaluations using their JKSimMet and Comminution Economic Evaluation Tool (CEET) simulation models respectively.

Lakefield's testing was conducted in two phases:

Four master composites were produced from the core samples for an initial flowsheet and design criteria development program. This indicated the mill flow sheet for Mirador will be a conventional copper-gold porphyry flowsheet, with relatively coarse primary SAG and ball mill grinding to about 150 µm followed by copper rougher flotation, concentrate regrind to 30 µm, and cleaner flotation and dewatering. Metallurgical testing and mineralogical quantitative modal liberation analysis, conducted by G&T, supported the selection of the primary grind and regrind parameters.

A recovery and mineralogical variability mapping program completed during the third quarter of 2004 subsequently confirmed that the metallurgy and mineralogy of the ore body is quite simple and homogenous, and the samples tested responded consistently well to the conventional flowsheet and reagent scheme selected. Over 44 variability sub-composite samples were produced from 17 drillholes and tested by hole and depth. Each sample was subjected to chemical and QemSCAN (Quantitative Evaluation of Mineralogy by Scanning Electron Microscopy) mineralogical analysis, grindability testing, and locked cycle flotation. Locked cycle concentrates were subjected to mineralogical, chemical, pyroforicity, and dewatering testing.

 

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Chemical analysis of the head samples indicated a range of copper grades from 0.20% to 1.07%, with average overall grade of 0.67%. Gold grades ranged from 0.05 g/t to 0.43 g/t with an average value of 0.22 g/t.

Concentrates produced are predicted to average 29.8% Cu at a recovery of 91%. The average gold grade and recovery was 5.2 g/t and 47.2%, respectively. A gold behaviour model developed from the flotation test data suggests gold tracks chalcopyrite, pyrite, and gangue, with near equal weighting throughout the process. There is good reconciliation between the test gold recovery data and that predicted by quantitative mineralogy.

A laboratory analysis of the individual locked cycle concentrate products indicated that no significant deleterious penalty element impurities were present and this is in good agreement with mineralogical mapping. Concentrate thickening and filtration testwork was conducted. The concentrates settled rapidly and no dewatering problems were identified. Pyroforicity results indicated the concentrate is not expected to be self-heating.

Grindability tests were conducted on the sub-composite intervals of core from individual drill holes. Two dedicated whole core geotechnical and comminution holes were also drilled and used for additional grinding testwork, including Bond Work and Abrasion Indices, JK drop-weight and MinnovEX SPI testing.

Most of the ore in the pit falls geologically in an alteration zone of intense gypsum depletion. This is indicated by low RQD data and poor rock quality observed in drill core boxes. Comparative Bond low energy impact (CWI) and drop-weight test data also indicates the +150 mm ore lumps will break relatively easily at low-energy, but that the resulting reduction may be small. On this basis it is reasonable to assume the SAG mill feed granulometry will be relatively finer than the copper porphyry industry average.

JK and SPI testing data ranked the samples in the medium range of resistance to impact breakage for SAG milling. The ore exhibits low to moderate abrasivity. The average Bond ball mill work index is about 14.5 kWh/t and ranks the ore in hardness to ball milling as moderately soft relative to other copper porphyry ores in Lakefield's industry database and with relatively low variability. The JKTech drop weight and SPI test SAG mill parameters, and ball mill work indices, were used in JK SimMet and CEET simulation software models to confirm the grinding circuit design basis, and there was good agreement between both approaches.

16.3     Mirador Deposit Flowsheet

The estimated mineral resources included in the mine plan total approximately 111 Mt grading 0.67% Cu and 0.22 g/t Au. [This mineral resource estimate has been superseded by the mineral resource estimates presented in the November 2006 MDA Technical Report] Silver and molybdenum are present but the grades are relatively low. Approximately 91 Mt of overlying waste rock will be removed over the mine life, resulting in an average strip ratio of 0.8:1. The process will be designed to treat 25,000 t/d of material.

 

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A simplified schematic drawing of the proposed flowsheet is provided in Figure [16.1]. Run-of-mine open pit ore will be crushed in a gyratory crusher. The crushed ore will be processed by means of semi-autogenous and ball mill grinding followed by rougher flotation, regrind, cleaner flotation, and dewatering to produce copper concentrate. The concentrate will be trucked via the existing road network in the area to a port facility in Machala for shipment to smelters. Tailings from the process will be impounded in a tailings pond; water will be reclaimed from the tailings pond and reused in the process.

16.4     Mirador Norte Metallurgy

MDA has reviewed the metallurgical sample locations that were chosen to characterize the various mineralized zones. Based on this quick assessment of the sample locations, it seems the samples are well chosen. For the supergene material, the samples are distributed regularly and throughout that zone. There were no samples of mixed material. The primary mineralization was well sampled in the southeast part of the deposit, but the northwest part of the deposit was not sampled at all; the northwest part of the deposit is much smaller in tonnage and is made up of two limbs.

Potential differences in metallurgical responses of upper enriched versus lower enriched zone material near their respective contacts may not be significant as much of the enriched zone will be mined together resulting in a blend. More important would be the effect of blending the enriched zone with leached material above and primary below. It is therefore suggested that some composited materials should be tested individually rather than as composites.

The greatest spatial changes in metallurgical characteristics at Mirador Norte, as at Mirador, are vertical, relatively rapid, and in and near the weathered rocks.

 

 

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Figure 16.1 Simplified Mirador Flowsheet

 

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17.0     MINERAL RESOURCE ESTIMATES

17.1     Introduction

Corriente requested in August 2006 that Mine Development Associates ("MDA") complete a resource update on the Mirador Project, to include the Mirador Norte deposit. The incentive for the update was the completion of 39 new drill holes at Mirador Norte in 2006. The Mirador Norte drill hole assay database contains 4,238 copper assays and 4,233 gold assays in 68 holes.

The work done by MDA included a review of Corriente's geologic model and a QA/QC analysis, resource estimation, pit optimization, and pit design.

17.2     Corriente Geologic Model

A combination of material types, mineral domains, and lithologic codes (listed in Table 17.1 and illustrated in Figure 17.1 and Figure 17.2) was used to control grade estimation and assign density values for both Mirador and Mirador Norte. Material-type domains consist of the leached, mixed, and enriched zones in the weathered profile. For copper, mineral domains included grade shells and lithologic groups (pre-mineral dikes, post-mineral dikes, and post-mineral breccias) in the hypogene mineralization. Copper was modeled separately in each of the three weathered zone material types. Gold and silver were modeled identically to copper in the hypogene material using the same copper-grade shells and lithologic groups, but were modeled differently from copper in the weathered zones. One of the most important geological differences between Mirador Norte and Mirador is that Mirador Norte dikes do not materially affect metal distributions.

The rock unit "brmn" at Mirador is the central breccia. While it is a distinct geologic unit, it has not been shown to have an effect on specific gravity, grades or metallurgy. Therefore, while it was modeled by solids, it was not used in any estimation and hence was not given a code.

At Mirador in the hypogene material, the main grade shell, used for copper, gold, and silver, is defined by the change from grades dominantly above ~0.4% Cu to grades dominantly below ~0.4% Cu. This shell appears to be related to stockwork-dominated mineralization (above ~0.4% Cu), as opposed to disseminated-dominated mineralization (below ~0.4% Cu). A clear, albeit gradational (~0.2% Cu to ~0.6% Cu) separation is shown on quantile plots of the copper distribution. To compensate for the gradational changes in grade, two more shells were defined at ~0.2% Cu and ~0.6% Cu. These shells were defined manually (as opposed to using estimation, i.e., using indicators, to account for local changes and variable drill hole and sample spacing).

At Mirador Norte in the hypogene material, the main grade shell, used for copper, gold, and silver, is defined by the change from grades dominantly above ~0.2% Cu to grades dominantly below ~0.2% Cu. A clear, albeit gradational (~0.12% Cu to ~0.4% Cu) separation is shown on quantile plots of the copper distribution. To compensate for the gradational changes in grade, two additional shells were manually defined at ~0.12% Cu and ~0.4% Cu. The porphyry dikes at Mirador Norte do not seem to affect the grades as they do at Mirador. No efforts have been made by Corriente to segregate these dikes in the modeling at Mirador Norte, nor is there reason to believe that they should be segregated. In many but not all cases, the porphyry dikes are mineralized in the same manner as the surrounding Zamora granite.

 

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If these dikes do have an effect on grades, then likely this effect is minimal. The differences in strength of mineralization may be caused by differential ground preparation.

Table 17.1 Coding and Description of the Geologic Model

Copper – Mirador

Code

Description

1000

Hypogene "unmineralized": the material outside the mineralized shell (200)

1200

Hypogene "mineralized": made up principally of disseminated and stockwork mineralization inside a shell defined by ~0.4 %Cu

1030

Early (pre-mineral) dikes (Jefp) which have similar though different styles of mineralization to the enclosing 1000 and 1200

1040

Late dikes (Jhbp) that post-date the mineralization

1050

Late breccias (brpm) that post-date the mineralization but have incorporated some mineralization during intrusion/stoping

2000

The enriched or supergene zone, which includes all lithologies

3000

The mixed zone, which includes all lithologies

4000

The leached zone, which includes all lithologies

Gold and Silver - Mirador

Code

Description

30

These are early (pre-mineral) dikes (Jefp) which have similar but somewhat different styles of mineralization to the enclosing 12340 and 12342

40

These are late dikes (Jhbp) that post-date the mineralization

50

These are late breccias (brpm) post-date the mineralization but have incorporated some mineralization during intrusion

12340

All (external to the previous zones) "unmineralized": this is the material outside the copper mineralized shell (200)3 and the dikes and late breccias

12342

All (external to the previous zones) "mineralized": this is made up principally of disseminated and stockwork mineralization4

Copper – Mirador Norte

Code

Description

1000

Hypogene "unmineralized": the material outside the mineralized shell (200)

1200

Hypogene "mineralized": made up principally of disseminated and stockwork mineralization inside a shell defined by ~0.2 %Cu

2000

The enriched or supergene zone, which includes all lithologies

3000

The mixed zone, which includes all lithologies

4000

The leached zone, which includes all lithologies

Gold and Silver – Mirador Norte

Code

Description

12340

All (external to the previous zones) "unmineralized": this is the material outside the copper mineralized shell (200)5

12342

All (external to the previous zones) "mineralized": this is made up principally of disseminated and stockwork mineralization6

3 A visual assessment suggests that this is an appropriate methodology and is consistent with the geology and mineralization of the deposit.
4 ditto
5 A visual assessment suggests that this is an appropriate methodology and is consistent with the geology and mineralization of the deposit.
6 ditto

 
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Figure 17.1 Schematic Illustration of Rock and Mineral Zones Used for Estimation - Copper

Figure 17.2 Schematic Illustration of Rock and Mineral Zones Used for Estimation–Gold and Silver

 
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In the enriched, mixed, and leached zones in both deposits, the copper has been remobilized and in general (at least apparently at the scale of the drilling) this leaching and remobilization did not affect the dikes and breccias. Gold seems to have maintained its original (pre-weathering) distribution. Silver distribution is most similar to gold distribution though a minor amount of remobilization does seem to have occurred7.

The style of mineralization just described gave rise to the following modeling criteria. In the weathered zones near the surface, there are sharp geologic and grade contacts between the hypogene and enriched types, and between the enriched or mixed and leached material types. These contacts were modeled using lithologic and grade criteria. All lithologies (i.e., dikes and breccias) in the enriched, mixed, and leached material types were treated for copper estimation as parts of each of the enriched, mixed or leached material types. In the hypogene rocks, each lithology (i.e., country rock, dikes, and breccias) was estimated separately for copper. Gold and silver modeling honored all lithology types while ignoring material types.

Corriente constructed solids for the above-described units (30, 40, 50, 1000, 1200, 2000, 3000, and 4000) in the Mirador deposit and for only the weathered units and the 0.2% Cu grade shell for Mirador Norte. While the weathering zones (1000, 2000, 3000, and 4000) were relatively simple and were used to clip each other to produce valid, non-overlapping solids, the porphyry dike and breccia solids (30, 40 and 50) were too complex for clipping because the solids overlap in too many ways. Therefore, a priority was assigned to these solids so that all coding was done in geologically chronological order (30 then 40 and then 50) for composite and block coding.

The previously described styles and interpretations of mineralization have statistical support. As there is sufficiently good statistical correlation between hypogene precious metals and copper, the same shells were used for both.

17.3     Sample Coding and Compositing

For Mirador, two grade shells (~0.2% Cu and ~0.6% Cu) were used to code samples, while only one shell (~0.4% Cu) was used for controlling the estimation and model block coding. Those samples lying outside the 0.6% Cu shell were used to estimate blocks outside the 0.4% Cu shell while those samples lying inside the 0.2% Cu shell were used to estimate grades inside the 0.4% Cu shell. Figure 17.1 and Figure 17.2 provide a schematic illustration of this. By coding and using samples in this manner, gradational changes were instilled in the model around the 0.4% Cu grade shell.

For Mirador Norte, two grade shells (~0.12% Cu and ~0.4% Cu) were used to code samples, while only one shell (~0.2% Cu) was used for controlling the estimation and model block coding. Those samples lying outside the 0.4% Cu shell were used to estimate blocks outside the 0.2% Cu shell while those samples lying inside the 0.12% Cu shell were used to estimate grades inside the 0.2% Cu shell. By coding and using samples in this manner, gradational changes were instilled in the model around the 0.2% Cu grade shell.


_____________________________
7 As the silver does not make a major contribution to the economics of the deposit and the remobilization is small enough, the lack of specific attention to remobilization during modeling is likely not an important omission.. There does, however, seem to be a slight enrichment of silver in the supergene-enriched zone and the users of the model should be cognizant of this.

 
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Overall, the mineralization style of both deposits is sufficiently evenly distributed to require little capping or estimation grade-projection restrictions. Sample descriptive statistics were calculated for copper, gold, and silver and are presented in Attachment C.

At Mirador, compositing was done to six meters (one-half of the final block size) honoring all material type, grade shell, and lithologic contacts after capping. The volume inside the main hypogene mineralization (~0.4% Cu shell) was estimated using composites from inside the 0.2% Cu shell. The volume outside the main hypogene mineralization (outside the ~0.4% Cu shell) was estimated using all composites from outside the 0.6% Cu shell.

At Mirador Norte, compositing was done to six meters (one-half of the block size in the vertical dimension) honoring all material type, grade shell, and lithologic contacts after capping. The volume inside the main hypogene mineralization (~0.2% Cu shell) was estimated using composites from inside the 0.12% Cu shell. The volume outside the main hypogene mineralization (outside the ~0.2% Cu shell) was estimated using all composites from outside the 0.4% Cu shell.

MDA checked Corriente's model coding with the lithologic coding and for the most part, the solids coding did in fact fairly portray the lithologic coding at Mirador. At Mirador Norte, checks were made comparing logged geologic units and the solids model supplied by Corriente. Material differences were noted and these were either explained, resolved or corrected in the solids.

17.4     Density

To determine the appropriate bulk rock densities to use in the resource model, MDA assessed the specific gravity (SG) measurements made in the field by Corriente in context of the defined lithologic and material types. Unless compelling reasons were found to change the methodology, MDA used the same methodology as in the pre-2005 estimates. MDA did have a different database and as a result, the mean specific gravity values of the various lithologies and material types were different than before. To determine reasonable density values, MDA adjusted the measured mean specific gravity of all samples downwards by 2% to account for the unavoidable sample selection bias8 introduced when choosing samples for field measurements. It was noted that the field samples were not oven dried before they were measured, hence MDA reduced the average specific gravities by 1%, 2%, 3%, and 4% for primary, enriched, mixed, and leached material, respectively for Mirador Norte. The adjusted specific gravities for each of these materials were then converted to density units (grams per cubic centimeter, g/cm3), based on the reasonable assumptions that the density of the water used in the field measurements was approximately 1.0 g/cm3, and that the porosity of the measured samples was negligible. Table 17.2 presents the mean density values of each unit.

_____________________________
8 When sampling for specific gravity testing, one can only test material that is intact, and not material that is broken, fractured, brecciated, etc. This type of material has lower specific gravity.

 
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Table 17.2 List of Specific Gravity Values Used in Model

Mirador

Zone/Lith

No. Samples

Density*

Density***

1000&1200

962

2.63**

2.58**

1030

142

2.65

2.60

1040

121

2.63

2.58

1050

103

2.61

2.56

2000

109

2.52

2.47

3000

75

2.46

2.41

4000

154

2.38

2.33

Mirador Norte

1000

317

2.58

2.50

2000

55

2.30

2.21

3000

25

2.45

2.33

4000

71

2.25

2.12

* before the 2% reduction;

** estimated into each block by inverse distance

 

*** post-2% reduction and post-reduction for humidity content at Corriente

Table 17.2 also lists the density data for Mirador Norte. For Mirador Norte, MDA analyzed the changes in the measured specific gravity with respect to down-hole depth and elevation. While MDA analyzed all the data together as well as segregated by primary material type primary, only the latter results are presented in this report (Figure 17.3 and Figure 17.4). The exclusion of the leached, mixed and supergene was done to see what effect weathering has on density of material below those three weathered material types. There is a subtle but real change in density with depth. This analysis guided MDA to the conclusion that the leached, mixed and enriched units can have their densities assigned to them globally, thereby mimicking gradational changes with depth. The graphs in Figure 17.3 and Figure 17.4 further suggest that gradational changes should occur in the primary mineralization. Given the number and distribution of density samples, MDA chose to estimate using a horizontally flattened sphere. Future estimates should evaluate the need to mimic topography with this type of estimation.

 
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Figure 17.3 Mirador Norte Density by Down-hole Depth

Figure 17.4 Mirador Norte Density by Elevation

 
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17.5     Resource Model and Estimation

The dikes and breccias (exclusive of the main central breccia) at the Mirador deposit are barren to weakly or erratically mineralized, and so are distinctly different from the main mineralization. No truly barren or weakly mineralized dikes have been intersected at Mirador Norte. The geological conditions in the Mirador deposit are probably much more complex than the interpretation in this model suggests, in spite of Corriente's valiant efforts to model pre- and post-mineral dikes and breccias accurately. There are likely slightly fewer tonnes and slightly higher grade in the Mirador resource than is estimated, but at the scale of mining this may or may not be noticeable.

The block model for Mirador was constructed with sub-blocks measuring 3.75 m by 3.75 m by 3 m (high). After estimation, the sub-blocks were re-blocked into blocks 15 m by 15 m by 12 m high; this is the same block size as the 2004 AMEC model. The model sub-blocked only when the contacts transected blocks. This procedure of re-blocking allows for better representation of the rapid grade changes across the pre- and post-mineral dikes and breccias and allows for local dilution at and across the contacts. If mining could execute effective grade control at block sizes of less than 15 m, then re-blocking the model to blocks smaller than 15 m by 15 m by 12 m (high) would be appropriate.

The Mirador Norte block model was also 15 m by 15 m by 12 m high but sub-blocking was not used. Instead, partials were used. Partials assign a percentage of each material type or grade domain to each block. Those partial percentages are used to weight-average grades and densities.

For Mirador, historic work by AMEC in 2004 emphasized geostatistics. MDA relied on AMEC's geostatistical results if nothing contradictory was found, but MDA still performed its own geostatistical studies to assess the applicability of the historic estimation parameters. Variograms were calculated for all zones, but only those with sufficient samples, which include the main mineralized zone and the surrounding low grade, could be modeled. The lack of sufficient samples, compounded by the fact that there might be poorer grade continuity, prevented the development of good variogram structures in the enriched, mixed, leached material types and in the post-mineral dikes and breccias. The variograms were used to support the chosen search ranges used in estimation. New variograms were calculated for Mirador Norte.

For Mirador Norte, MDA used inverse distance estimation for the reported resource estimate. MDA used the newly calculated variograms to guide the search ranges for Mirador Norte. During this study, it was found that while copper does display some anisotropy (400 m in a northeast direction and 200 m in the northwest direction), gold and silver grade distributions are isotropic.

MDA estimated numerous models for Mirador to assess the impacts of:

As Mirador Norte, a relatively simpler deposit, MDA ran several models using different estimation parameters and methods.

For Mirador, MDA estimated two models for each of those parameters listed above; one used inverse-distance squared and one used the nearest-neighbor method. Modifications were made to the final estimate based on the results and comparisons of each of the interim models. No Kriging was done, as most zones did not produce variogram structures that could be modeled. The estimation parameters used in the final Mirador estimate are given in Table 17.3, Table 17.4, and Table 17.5.

 
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For Mirador Norte, MDA estimated three models for copper and three for gold; these were a kriged model, an inverse-distance squared model and a nearest-neighbor model. The comparison was considered good. The estimation parameters used in the final estimate for Mirador Norte are given in Table 17.6 and Table 17.7.

Initially, MDA used an inverse distance power of three (ID3) for Mirador and noted a rather steep relative drop in the amount of material grading over 0.7% Cu compared to the previous AMEC estimate, which used the power of eight in inverse distance estimation. This latter high power has a tendency to eliminate smoothing, approaching a nearest neighbor or polygonal estimate. Because the Mirador deposit has few high-grade outliers and is a relatively well-behaved deposit with respect to grade continuity, MDA felt that a lower power would be more appropriate. Due to a desire to maintain a certain amount of continuity in estimation techniques, MDA assessed the differences in estimation parameters9. The model was run at inverse powers of 3, 4, and 8 to study the sensitivities to heavily localizing the estimation. Based on the results of comparisons of these other models and on point validation studies, there was no compelling reason to choose ID3 over ID4. Therefore, ID4 methodology was chosen to maintain a certain amount of consistency with previous estimates, while also aiming to move away from a polygonal type of estimate. Examples of the copper and gold grade models for Mirador are given in Figure 17.5 and Figure 17.6.

MDA used an inverse distance power of three (ID3) at Mirador Norte. Examples of the copper and gold grade models for Mirador Norte are given in Figure 17.7 and Figure 17.8. Because of the low silver grades and the few samples with silver assays, modeling results are not reported for silver.

 

_____________________________
9 Search distance, inverse distance power, number of samples, minimum number of samples, and maximum number of samples per hole.

 
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Table 17.3 Mirador: Estimation Parameters for Copper by Mineral Domain

Description

Parameter

Main Hypogene Mineralization – disseminated low-grade (12340) Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor

200 / 200 / 200

Inverse distance power

4

High-grade restrictions

None

Main Hypogene Mineralization – disseminated and stockwork (12342): Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 200

Inverse distance power

4

High-grade restrictions

None

Enriched Mineralization – (2000) Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 50

Inverse distance power

4

High-grade restrictions

None

Mixed Mineralization – (3000) Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 50

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

None

Leached Zone – (4000) Copper – Pass 1

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 50

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

Only comps <=0.2% Cu

Leached Zone – (4000) Copper – Pass 2

Samples: minimum/maximum/maximum per hole

2 / 14 / 5

Rotation/Dip/Tilt (searches)

140o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

20 / 20 / 20

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

None

 
Mine Development Associates  
December 11, 2006

 

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 100
 

Table 17.3 Estimation Parameters for Copper by Mineral Domain (continued)

Description

Parameter

Pre-Mineral Porphyry – disseminated and stockwork (30, Jefp): Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

110o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

None

Post-Mineral Porphyry (40, Jhbp): Copper – Pass 1

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

140o / -90o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

Only comps <=0.1% Cu

Post-Mineral Porphyry (40, Jhbp): Copper – Pass 2

Samples: minimum/maximum/maximum per hole

2 / 14 / 5

Rotation/Dip/Tilt (searches)

140o / -90o / 0o

Search (m): major/semimajor/minor (vertical)

20 / 20 / 20

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

None

Post-Mineral Breccia (50, brpm): Copper – Pass 1

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

130o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

Only comps <=0.1% Cu

Post-Mineral Breccia (50, brpm): Copper – Pass 2

Samples: minimum/maximum/maximum per hole

2 / 14 / 5

Rotation/Dip/Tilt (searches)

130o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

20 / 20 / 20

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

None

 
Mine Development Associates  
December 11, 2006

 

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Corriente Resources
 

Page 101
 

Table 17.4 Mirador: Estimation Parameters for Gold by Mineral Domain

Main Hypogene Mineralization – disseminated low-grade (12340) Gold

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor

200 / 200 / 200

Inverse distance power

4

High-grade restrictions

None

Main Hypogene Mineralization – disseminated and stockwork (12342): Gold

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 200

Inverse distance power

4

High-grade restrictions

None

Pre-Mineral Porphyry – disseminated and stockwork (30, Jefp): Gold

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

110o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in ppb Au and distance in m)

None

Post-Mineral Porphyry (40, Jhbp): Gold – Pass 1

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

140o / -90o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in ppb Au and distance in m)

Only comps <=40 ppb Au

Post-Mineral Porphyry (40, Jhbp): Gold – Pass 2

Samples: minimum/maximum/maximum per hole

2 / 14 / 5

Rotation/Dip/Tilt (searches)

140o / -90o / 0o

Search (m): major/semimajor/minor (vertical)

20 / 20 / 20

Inverse distance power

4

High-grade restrictions (grade in ppb Au and distance in m)

None

Post-Mineral Breccia (50, brpm): Gold – Pass 1

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

130o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in Cu% and distance in m)

Only comps <=40 ppb Au

Post-Mineral Breccia (50, brpm): Gold – Pass 2

Samples: minimum/maximum/maximum per hole

2 / 14 / 5

Rotation/Dip/Tilt (searches)

130o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

20 / 20 / 20

Inverse distance power

4

High-grade restrictions (grade in ppb Au and distance in m)

None

 
Mine Development Associates  
December 11, 2006

 

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Corriente Resources
 

Page 102
 

Table 17.5 Mirador: Estimation Parameters for Silver by Mineral Domain

Main Hypogene Mineralization – disseminated low-grade (12340) Silver

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor

200 / 200 / 200

Inverse distance power

4

High-grade restrictions

None

Main Hypogene Mineralization – disseminated and stockwork (12342): Silver

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 200

Inverse distance power

4

High-grade restrictions

None

Pre-Mineral Porphyry – disseminated and stockwork (30, Jefp): Silver

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

110o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in ppm Ag and distance in m)

None

Post-Mineral Porphyry (40, Jhbp): Silver – Pass 1

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

140o / -90o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in ppm Ag and distance in m)

Only comps <=0.4 ppm Ag

Post-Mineral Breccia (40, Jhbp): Silver – Pass 2

Samples: minimum/maximum/maximum per hole

2 / 14 / 5

Rotation/Dip/Tilt (searches)

140o / -90o / 0o

Search (m): major/semimajor/minor (vertical)

20 / 20 / 20

Inverse distance power

4

High-grade restrictions (grade in ppm Ag and distance in m)

None

Post-Mineral Breccia (50, brpm): Silver – Pass 1

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

130o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 100

Inverse distance power

4

High-grade restrictions (grade in ppm Ag and distance in m)

Only comps <=0.4 ppm Ag

Post-Mineral Porphyry (50, brpm): Silver – Pass 2

Samples: minimum/maximum/maximum per hole

2 / 14 / 5

Rotation/Dip/Tilt (searches)

130o / -90o / 0o

Search (m): major/semimajor/minor ("vertical")

20 / 20 / 20

Inverse distance power

4

High-grade restrictions (grade in ppm Ag and distance in m)

None

 
Mine Development Associates  
December 11, 2006

 

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Corriente Resources
 

Page 103
 

Table 17.6 Mirador Norte: Estimation Parameters for Copper by Mineral Domain

Description

Parameter

Main Hypogene Mineralization – outside the 0.2% Cu shell (1000) Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor

200 / 200 / 80

Inverse distance power

3

High-grade restrictions

None

Main Hypogene Mineralization – inside the 0.2% Cu shell (1200) Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 80

Inverse distance power

3

High-grade restrictions

None

Enriched Mineralization – (2000) Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor ("vertical")

200 / 200 / 50

Inverse distance power

3

High-grade restrictions

None

Mixed Mineralization – (3000) Copper

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor (vertical)

150 / 150 / 40

Inverse distance power

3

High-grade restrictions (grade in Cu% and distance in m)

None

Leached Zone – (4000) Copper – Pass 1

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

90o / 0o / 0o

Search (m): major/semimajor/minor ("vertical")

150 / 150 / 40

Inverse distance power

3

High-grade restrictions (grade in Cu% and distance in m)

Only comps <=0.1% Cu

Leached Zone – (4000) Copper – Pass 2

Samples: minimum/maximum/maximum per hole

2 / 14 / 5

Rotation/Dip/Tilt (searches)

90o / 0o / 0o

Search (m): major/semimajor/minor ("vertical")

20 / 20 / 20

Inverse distance power

3

High-grade restrictions (grade in Cu% and distance in m)

None

 
Mine Development Associates  
December 11, 2006

 

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 103
 

Table 17.7 Mirador Norte: Estimation Parameters for Gold by Mineral Domain

Main Hypogene Mineralization – disseminated low-grade (12340) Gold

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

0o / 0o / 0o

Search (m): major/semimajor/minor

200 / 200 / 80

Inverse distance power

3

High-grade restrictions

None

Main Hypogene Mineralization – disseminated and stockwork (12342): Gold

Samples: minimum/maximum/maximum per hole

1 / 14 / 4

Rotation/Dip/Tilt (searches)

30o / 0o / 0o

Search (m): major/semimajor/minor (vertical)

200 / 200 / 80

Inverse distance power

3

High-grade restrictions

None

 

 

 

 
Mine Development Associates  
December 11, 2006

 

 

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 109
 

17.6     Resources

The Mirador and Mirador Norte resources used CIM classifications. For consistency and a lack of compelling reasons to do otherwise, the Mirador resource classification used the same criteria as previous estimates, except that MDA considered that some material should be classified as Measured. Because copper adds the greatest value of both deposits, all classification is based on the copper while gold and silver are carried along with the copper. The classification criteria are presented in Table 17.8 for Mirador and for Mirador Norte. While there is gold in the leached zone in both deposits, all blocks in the leached zones are unclassified for metallurgical reasons and there is no plan to extract gold from the leached zone in either deposit.

For Mirador, the inclusion of Measured material in this resource update demonstrates an increased level of confidence, conveyed by the observations that a) the geology is relatively well understood; b) grade continuity is good; c) the deposit is relatively predictable; and d) the sampling is of good quality. On the other hand, the relatively small amount of Measured material (~15% of the total Measured and Indicated) is a consequence of the need to portray some of the risks incorporated in the model, which are the consequence of these facts:

There is no Measured material at Mirador Norte. This is in part because the drill spacing is still relatively wide and because this is the first resource estimate for Mirador Norte. The resource tabulation for the Mirador deposit alone is presented in Tables 17.9 to Table 17.12. The resource for the Mirador Norte deposit alone is presented in Table 17.13 to Table 17.14 and a breakdown by material type is in Table 17.15. Example sections for Mirador and Mirador Norte are given in Figure 17.9 and Figure 17.10, respectively.

 

Mine Development Associates  
December 11, 2006  

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Corriente Resources
 

Page 110
 

Table 17.8 Criteria for Resource Classification

MIRADOR

All – Measured

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 20

Hypogene – Indicated

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 100

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 35

Enriched (supergene) and Mixed – Indicated

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 75

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 35

All material not classified above is Inferred

MIRADOR NORTE

All – Measured

Minimum no. of samples /minimum no. of holes / maximum distance (m)

None

Hypogene – Indicated

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 100 *

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 50 **

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 35

Enriched (supergene) and Mixed – Indicated

 

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 2 / 75

Or

Minimum no. of samples /minimum no. of holes / maximum distance (m)

2 / 1 / 35

Material not classified above is Inferred unless beyond 50 m of a sample outside the 0.12% Cu shell

Leached – modeled but unclassified; all Leached material is considered to be waste

* inside the 0.12% Cu shell; ** outside the 0.12% Cu shell

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 113
 

Table 17.9 Mirador Copper, Gold and Silver Resources – Measured

Total Measured

Cutoff

Tonnes

Cu (%)

lbs Cu

Au (ppb)

oz Au

Ag (ppm)

oz Ag

0.30

62,680,000

0.60

831,000,000

200

400,000

1.5

3,080,000

0.35

57,610,000

0.63

795,000,000

200

380,000

1.6

2,930,000

0.40

52,610,000

0.65

753,000,000

210

360,000

1.6

2,770,000

0.45

47,900,000

0.67

709,000,000

220

330,000

1.7

2,590,000

0.50

42,810,000

0.69

656,000,000

220

310,000

1.7

2,370,000

0.55

36,620,000

0.72

584,000,000

230

270,000

1.8

2,090,000

0.60

30,360,000

0.75

505,000,000

240

230,000

1.8

1,790,000

0.65

24,440,000

0.79

424,000,000

240

190,000

1.9

1,480,000

0.70

18,140,000

0.83

330,000,000

250

150,000

1.9

1,130,000

0.75

11,950,000

0.88

231,000,000

260

100,000

2.0

769,000

0.80

7,910,000

0.93

162,000,000

270

68,000

2.1

522,000

0.85

5,090,000

0.99

111,000,000

270

44,000

2.1

340,000

0.90

3,220,000

1.06

75,000,000

290

30,000

2.1

215,000

0.95

2,000,000

1.14

50,000,000

300

20,000

2.0

131,000

1.00

1,470,000

1.21

39,000,000

310

15,000

2.0

97,000

Cutoff in %Cu

Table 17.10 Mirador Copper, Gold and Silver Resources – Indicated

Total Indicated

Cutoff

Tonnes

Cu (%)

lbs Cu

Au (ppb)

oz Au

Ag (ppm)

oz Ag

0.30

491,510,000

0.55

5,958,000,000

180

2,810,000

1.4

21,970,000

0.35

441,080,000

0.58

5,596,000,000

180

2,610,000

1.4

20,530,000

0.40

385,060,000

0.60

5,134,000,000

190

2,380,000

1.5

18,760,000

0.45

335,680,000

0.63

4,672,000,000

200

2,150,000

1.6

16,890,000

0.50

283,610,000

0.66

4,126,000,000

210

1,890,000

1.6

14,770,000

0.55

230,250,000

0.69

3,507,000,000

210

1,590,000

1.7

12,400,000

0.60

176,780,000

0.73

2,831,000,000

220

1,260,000

1.7

9,910,000

0.65

129,500,000

0.76

2,181,000,000

230

950,000

1.8

7,560,000

0.70

90,220,000

0.80

1,598,000,000

240

680,000

1.9

5,420,000

0.75

55,700,000

0.85

1,047,000,000

240

435,000

1.9

3,441,000

0.80

33,300,000

0.91

666,000,000

250

270,000

2.0

2,124,000

0.85

18,670,000

0.97

401,000,000

260

157,000

2.0

1,208,000

0.90

10,700,000

1.05

248,000,000

270

92,000

2.1

710,000

0.95

6,650,000

1.13

165,000,000

270

57,000

2.1

452,000

1.00

4,550,000

1.20

120,000,000

270

40,000

2.1

308,000

Cutoff in %Cu

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 114
 

Table 17.11 Mirador Copper, Gold and Silver Resources – Measured and Indicated

Total Measured and Indicated

 

 

 

 

 

Cutoff

Tonnes

Cu (%)

lbs Cu

Au (ppb)

oz Au

Ag (ppm)

oz Ag

0.30

554,190,000

0.56

6,789,000,000

180

3,210,000

1.4

25,050,000

0.35

498,690,000

0.58

6,391,000,000

190

2,990,000

1.5

23,460,000

0.40

437,670,000

0.61

5,887,000,000

190

2,740,000

1.5

21,530,000

0.45

383,580,000

0.64

5,381,000,000

200

2,480,000

1.6

19,480,000

0.50

326,420,000

0.66

4,782,000,000

210

2,200,000

1.6

17,140,000

0.55

266,870,000

0.70

4,091,000,000

220

1,860,000

1.7

14,490,000

0.60

207,140,000

0.73

3,336,000,000

220

1,490,000

1.8

11,700,000

0.65

153,940,000

0.77

2,605,000,000

230

1,140,000

1.8

9,040,000

0.70

108,360,000

0.81

1,928,000,000

240

830,000

1.9

6,550,000

0.75

67,650,000

0.86

1,278,000,000

250

535,000

1.9

4,210,000

0.80

41,210,000

0.91

828,000,000

260

338,000

2.0

2,646,000

0.85

23,760,000

0.98

512,000,000

260

201,000

2.0

1,548,000

0.90

13,920,000

1.05

323,000,000

270

122,000

2.1

925,000

0.95

8,650,000

1.13

215,000,000

280

77,000

2.1

583,000

1.00

6,020,000

1.20

159,000,000

280

55,000

2.1

405,000
Cutoff in %Cu

*total Measured plus Indicated were calculated from rounded Measured and rounded Indicated resources and hence some apparent differences are rounding related.

Table 17.12 Mirador Copper, Gold and Silver Resources –Inferred

Total Inferred

 

 

 

 

 

 

 

Cutoff

Tonnes

Cu (%)

lbs Cu

Au (ppb)

oz Au

Ag (ppm)

oz Ag

0.30

417,300,000

0.45

4,124,000,000

150

1,960,000

1.1

15,130,000

0.35

338,390,000

0.48

3,559,000,000

150

1,670,000

1.2

13,220,000

0.40

235,400,000

0.52

2,708,000,000

170

1,250,000

1.3

9,900,000

0.45

175,230,000

0.56

2,147,000,000

180

980,000

1.4

7,820,000

0.50

122,290,000

0.59

1,593,000,000

180

710,000

1.5

5,790,000

0.55

70,270,000

0.64

993,000,000

190

440,000

1.5

3,470,000

0.60

37,890,000

0.71

587,000,000

190

230,000

1.6

1,970,000

0.65

22,020,000

0.76

369,000,000

190

140,000

1.7

1,200,000

0.70

14,710,000

0.81

260,000,000

190

90,000

1.8

824,000

0.75

9,450,000

0.85

177,000,000

200

60,000

1.9

561,000

0.80

5,750,000

0.90

114,000,000

210

39,000

2.0

370,000

0.85

4,020,000

0.93

82,000,000

210

28,000

2.1

266,000

0.90

2,530,000

0.96

54,000,000

210

17,000

2.1

170,000

0.95

1,290,000

1.00

28,000,000

220

9,000

2.2

90,000

1.00

530,000

1.04

12,000,000

220

4,000

2.2

38,000

Cutoff in %Cu

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 115
 

Table 17.13 Mirador Norte Copper and Gold Resources – Indicated

Indicated Resource

 

 

 

 

%Cu Cutoff

Tonnes

%Cu

lbs Cu

Au ppb

oz Au

0.30

289,560,000

0.44

2,820,000,000

80

745,000

0.35

231,050,000

0.47

2,407,000,000

85

630,000

0.40

171,410,000

0.51

1,921,000,000

89

489,000

0.45

119,090,000

0.55

1,435,000,000

93

357,000

0.50

70,980,000

0.60

938,000,000

99

225,000

0.55

39,830,000

0.66

582,000,000

101

130,000

0.60

21,520,000

0.74

353,000,000

105

73,000

0.65

13,530,000

0.82

245,000,000

108

47,000

0.70

9,620,000

0.88

187,000,000

106

33,000

0.75

7,310,000

0.93

150,000,000

103

24,000

0.80

5,880,000

0.97

126,000,000

102

19,000

0.85

4,680,000

1.01

105,000,000

100

15,000

0.90

3,690,000

1.05

86,000,000

99

12,000

0.95

2,790,000

1.10

68,000,000

100

9,000

1.00

2,230,000

1.13

55,000,000

97

7,000

Table 17.14 Mirador Norte Copper and Gold Resources – Inferred

Inferred Resource

 

 

 

 

%Cu Cutoff

Tonnes

%Cu

lbs Cu

Au ppb

oz Au

0.30

105,040,000

0.41

957,000,000

67

225,000

0.35

71,560,000

0.46

720,000,000

69

158,000

0.40

45,820,000

0.51

513,000,000

68

101,000

0.45

29,890,000

0.55

366,000,000

71

68,000

0.50

18,960,000

0.60

253,000,000

75

46,000

0.55

12,950,000

0.64

184,000,000

77

32,000

0.60

7,420,000

0.70

114,000,000

78

19,000

0.65

3,250,000

0.81

58,000,000

97

10,000

0.70

2,000,000

0.90

40,000,000

111

7,000

0.75

1,690,000

0.94

35,000,000

116

6,000

0.80

1,390,000

0.98

30,000,000

119

5,000

0.85

1,130,000

1.01

25,000,000

122

4,000

0.90

900,000

1.05

21,000,000

124

4,000

0.95

730,000

1.08

17,000,000

123

3,000

1.00

490,000

1.13

12,000,000

128

2,000

Table 17.15 Mirador Norte Copper and Gold Resources – by Material Type

Indicated Resource: Primary

Indicated Resource: Enriched

Indicated Resource: Mixed

Tonnes

%Cu

Au ppb

Tonnes

%Cu

Au ppb

Tonnes

%Cu

Au ppb

159,100,000

0.49

89

10,460,000

0.79

83

1,860,000

0.59

94

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Inferred Resource: Primary

Inferred Resource: Enriched

Inferred Resource: Mixed

Tonnes

%Cu

Au ppb

Tonnes

%Cu

Au ppb

Tonnes

%Cu

Au ppb

42,530,000

0.49

66

3,040,000

0.78

99

240,000

0.53

86

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 116
 

For the Mirador deposit, it is important to note that:

Consequently, MDA has reported resources to the 750 m elevation and no deeper in spite of the indications that the mineralization is open to depth. Pit optimization shells bottom out at 650 m elevation (the bottom of the estimated model) when considering the Inferred material in the pit optimization and using "reasonable but optimistic" pit optimization parameters, 200 m below the deepest drill intercept. Checks were made on the Mirador resource model in the following manner:

It became evident from comparing the models that several factors impacted the 2005 model relative to the 2004 model. These are described in order of decreasing impact.

1.     The greatest impact on the changes to estimated resources was caused by more rigid controls on the estimation through the use of better-defined grade and lithologic shells manually modeled rather than indicator modeled.

2.     The 2005 drill holes, which were located principally along the margins of the deposit, had the effect of limiting the projection of the higher grades and decreasing the mean grade of the resource. The 2005 drilling was the only reason for the large increase in Indicated material. The new drilling and continued efforts by Corriente allow for the inclusion of Measured material in this resource estimate update.

3.     The incorporation of dilution along the margins of the mineralized material affected the overall grade in a negative way, thereby more closely approaching what will be mined on blocks of 15 m by 15 m.

4.     The change from ID8 to ID4 reduced the tonnage of the higher-grade (over ~0.7%Cu) material due to allowing for some grade averaging (smoothing) during estimation.

For the Mirador Norte resource model, a separate resource estimate was made using kriging and nearest neighbor estimates. The results were sufficiently similar to support the presented model results.

 

________________________
10 Note that there is an increase in total tonnes for all categories at a cutoff of 0.4%Cu of 50 million.

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 117
 

17.7     Discussion, Qualifications, Risk and Recommendations

For the Mirador deposit, the most important observation that can be presented to the reader is the likelihood that geological reality is more complex with respect to breccias and dikes than is portrayed in the resource model. This could have an effect (assuming perfect grade control) of presenting the mill with less tonnes at higher grade during production. Other noteworthy points respecting the Mirador deposit are presented below.

Vertical dikes and breccias Corriente has begun drilling more angle holes minimizing the risks associated with the vertical drill holes and vertical post- and syn-mineralization dikes and breccias. A certain amount of risk remains in this resource estimate because of the inability to fully assess location, quantity and width of the near-vertical dikes and breccias.

Solids While Corriente made valiant efforts at making solids to define the dikes and breccias, the solids contained numerous variably overlapping volumes of space within their geometries. Because the solids were not modeled so that any given space is only occupied by one solid, a certain number of "work-arounds" were necessary in the modeling process. While MDA believes that there are no material errors or biases instilled in this model by modeling on screen and directly via solids, a cross-sectional model taken to plan would have added confidence, precision, and accuracy. Corriente should take the time to slice the lithology and grade shell solids to section and plan, and edit accordingly to produce non-overlapping interpretations, as well as to refine inaccurate geometries introduced by the solids modeling. If the sections and plans remain relatively simple, then the solids could be reconstructed from the validated and modified level plans.

Sample Grade Reproducibility Rather large discrepancies exist in gold pulp duplicate assays and larger discrepancies exist in the coarse reject duplicate assays. Likely, this reproducibility would be worse at the core sample splitting stage. The information does not imply an inherent bias, as the overall mean gold grade should be correct. MDA suggests that a small program (about fifty samples) of metallic screen assaying be done in order to make a preliminary assessment of the reproducibility of gold grades, optimum sample sizes, and sub-sampling procedures.

Modeling Future modeling should consider using a partial-block model instead of a sub-block model, which would require valid and non-overlapping solids or taking the model to plan levels matching the block height.

Other Metals Additional study is warranted to assess the possibility and magnitude of mobilization and potential enrichment of silver mineralization. While this does not appear to be of great importance, as silver provides relatively small amounts of value in the overall economics of the deposit, it is worthy of a modest study to assess this and determine if modeling should be done differently. Future study and possible estimation should be focused on the modes of occurrence of molybdenum and zinc (and other elements) as providing some potential economic impact, positive (e.g., molybdenum) or negative (e.g., zinc).

Mirador Norte For the Mirador Norte deposit, probably the greatest potential cause of uncertainty in the resource model is the relatively wide drill spacing.

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 118
 

18.0     OTHER RELEVANT DATA AND INFORMATION

Other relevant data and information for the Mirador project are published in the report titled "Mirador Copper Project Feasibility Study Report" (AMEC, 2005). This feasibility study is relevant because it provides details on infrastructure, costs, potential mining and processing methods, all of which are relevant to the exploitation of the resources and reserves updated and described in this report.

The density factors used in the January 2006 Mirador model were based on density measurements from un-dried samples. While this will have some but little effect on the primary mineralization, which is by far the bulk of the reserve, it will reduce the enriched tonnage and mixed tonnage more than the primary. There is no information on which to base an adjustment factor, but it is expected that the adjustment would be approximately one or two percentage points for the primary sulfide mineralization and it could be two to four percentage points for the weathered rock. Due to the higher porosity of leached material (waste), the reduction in tonnage would likely be greater for this material than for the enriched zone (mineralized rock).

The following discussion on economic assessments, which is taken directly from the May 2006 NI 43-101 Technical Report is still considered valid. Corriente is presently undertaking an updated feasibility study, and depending on the conclusions of that study the economic evaluations may change.

18.1     Introduction

MDA generated a series of floating cone pit shells from the MDA Measured and Indicated resource described in this report using the AMEC May, 2005 Mirador Copper Project Feasibility Study economics and pit slope angles. Two production schedules were generated from the $1.00 per pound copper price pit shell. The first schedule assumed 25,000 tonnes per day to the mill for the life of the mine and the second schedule started with 25,000 tonnes per day, which was increased to 50,000 tonnes per day in year 6. Corriente personnel then created financial models using these production schedules.

In the AMEC feasibility study the ultimate pit size was limited to a total of 110 million "ore" tonnes, which equates to about a 12-year mine life at 25,000 "ore" tonnes per day. MDA did not restrict the pit size due in part to a change in the maximum pit wall height and therefore the comparable pit shell is significantly larger. Note the use of the term "ore" is taken from the AMEC feasibility report.

18.2     Floating Cone Analyses

MDA used the MineSight® Lerchs-Grossmann "floating cone" algorithm to produce open-pit cone shells using the parameters shown in Table 18.1. All of these physical and economic parameters are the same as the ones in the AMEC feasibility study. Only Measured and Indicated materials were allowed to make positive economic contributions; Inferred material was considered waste. Net block values were calculated for, and coded into each block in the model below topography, with waste blocks receiving negative numbers equivalent to the cost of mining. The same calculations were used to determine the cutoff between mill feed and waste. The resulting cutoff grade for the base case ($1.00/lb Cu price), assuming only copper revenue, is 0.37% Cu. Because recovered gold contributes value, the actual cutoff is slightly lower depending on the gold grade. Multiple cone runs were made to test for sensitivity to metals prices and the results are summarized in Table 18.2.

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 119
 

Table 18.1 Floating Cone Parameters

Item

Value

Copper Processing

 

 

Mill recovery %

 

91.4%

Concentrate grade %

 

30%

Concentrate moisture %

 

8%

Concentrate losses %

 

0.25%

Concentrate transport $/WMT

$

81.62

Concentrate transport $/DMT

$

88.72

Smelting $/DMT

$

75.00

Smelter recovery %

 

96.5%

Refining $/lb

$

0.08

Gold Processing

 

 

Mill recovery %

 

47%

Smelter payable %

 

95%

Refining $/oz

$

6.00

Process cost with G&A $/DMT

$

3.90

Mining $/DMT

$

0.89

Copper price $/lb

$

0.65-$1.50

Gold price $/oz

$

400

Overall pit slope angles

 

35°-42°

DMT = Dry Metric Tonne

 

 

WMT = Wet Metric Tonne

 

 

Table 18.2 Floating Cone Results

Cu price

Tonnes > cut (Measured & Indicated only)

Waste tns

Total tns

 

$/lb

x1000

Cu %

Au g/t

Ag g/t

x1000

x1000

strip ratio

$0.65

5,178

1.12

0.249

1.89

11,149

16,327

2.15

$0.70

13,070

0.93

0.258

1.81

16,673

29,743

1.28

$0.75

39,203

0.81

0.242

1.89

41,073

80,276

1.05

$0.80

77,386

0.74

0.228

1.85

77,662

155,048

1.00

$0.85

156,852

0.69

0.217

1.74

204,306

361,158

1.30

$0.90

242,767

0.66

0.207

1.67

336,497

579,264

1.39

$0.95

291,052

0.64

0.201

1.62

394,849

685,901

1.36

$1.00

346,995

0.62

0.196

1.57

491,393

838,388

1.42

$1.05

388,341

0.60

0.192

1.52

556,834

945,175

1.43

$1.10

416,382

0.59

0.188

1.49

587,276

1,003,658

1.41

$1.15

440,912

0.58

0.185

1.47

612,894

1,053,806

1.39

$1.20

464,423

0.57

0.183

1.44

647,144

1,111,567

1.39

$1.25

487,622

0.56

0.180

1.42

681,837

1,169,459

1.40

$1.30

503,816

0.55

0.178

1.41

698,646

1,202,462

1.39

$1.35

520,022

0.54

0.176

1.39

710,333

1,230,355

1.37

$1.40

534,064

0.54

0.174

1.38

738,935

1,272,999

1.38

$1.45

544,040

0.53

0.173

1.37

755,431

1,299,471

1.39

$1.50

551,465

0.53

0.172

1.36

763,612

1,315,077

1.38

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 120
 

Slope angles varied by sector as follows (from AMEC feasibility, 2005).

For feasibility purposes, the following inter-ramp slopes are recommended by zone (where 0° due North, 90° due East):

Zone I (330° to 60°) ..........................35°
Zone II (60° to 150°) ........................42°
Zone III (150° to 180°) .....................40°
Zone IV (180° to 270°).....................38°
Zone V (270° to 330°)......................40°

The slopes suggested above are preliminary estimates only and may be modified with additional geotechnical drilling, during subsequent design work and trial excavations during the early stages of mining.

Work done by Piteau Associates, a geotechnical consulting firm based in Vancouver B.C., after the AMEC feasibility was completed, indicated that the overall pit depth restriction of 500m can be eliminated if 30m wide catch benches are placed in the slope every 200m of elevation. Specifically, Zones III and IV would have slopes higher than 500m and would require the extra catch benches. The overall slope angles updated by Piteau are slightly steeper than the AMEC angles but the AMEC angles were used in the floating cones to be consistent with the AMEC work. Piteau is in the process of finalizing their work and refinements to the slope angles and design criteria are possible.

18.3     Production Schedules

MDA divided the ultimate pit shell into four phases to approximate the phases of a designed pit. The floating cone shell at a copper price of $0.72 per pound, containing 43 million total tonnes, was used as a starter pit. Subsequent phase shells were at least 100 m from the previous shell to allow enough potential mining width. Phase 2 contains 112 million tonnes, phase 3 contains 206 million tonnes and phase 4 contains 477 million tonnes. Two production schedules were created; the first at 25,000 tonnes per day (tpd) mill feed and the second starting at 25,000 mill tonnes per day increasing to 50,000 tonnes per day in year 6. The schedules are shown in Table 18.3 and Table 18.4.

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 121
 

Table 18.3 25,000 Tonnes per Day Production Schedule

Period (year)

-1

1

2

3

4

5

6

7

8

9

10

11

12

 

Mill kt

0

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

 

Cu grade %

0.000

0.852

0.765

0.729

0.633

0.599

0.606

0.582

0.560

0.597

0.615

0.612

0.637

 

Au grade g/t

0.176

0.219

0.240

0.252

0.230

0.221

0.180

0.187

0.203

0.226

0.228

0.193

0.207

 

Ag grade g/t

1.52

1.88

1.63

1.68

2.09

1.93

1.87

1.75

1.40

1.48

1.55

1.49

1.61

 

Waste kt

5,000

11,341

6,189

15,811

18,250

18,935

9,125

10,912

11,552

9,125

10,577

5,418

42,007

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Period (year)

13

14

15

16

17

18

19

20

21

22

23

24

25

 

Mill kt

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

 

Cu grade %

0.680

0.677

0.619

0.598

0.589

0.596

0.617

0.645

0.628

0.500

0.501

0.548

0.562

 

Au grade g/t

0.213

0.213

0.182

0.166

0.173

0.191

0.197

0.193

0.181

0.176

0.190

0.204

0.206

 

Ag grade g/t

1.62

1.85

1.61

1.70

1.87

1.74

1.46

1.59

1.51

1.13

1.16

1.25

1.21

 

Waste kt

13,036

10,356

10,869

15,330

9,125

9,125

9,125

9,125

37,680

45,884

21,036

18,122

15,841

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Period (year)

26

27

28

29

30

31

32

33

34

35

36

37

38

39

Mill kt

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

9,125

218

Cu grade %

0.583

0.594

0.599

0.606

0.615

0.631

0.622

0.613

0.627

0.621

0.621

0.599

0.579

0.581

Au grade g/t

0.202

0.195

0.187

0.178

0.174

0.181

0.184

0.186

0.193

0.199

0.195

0.164

0.126

0.117

Ag grade g/t

1.26

1.37

1.54

1.60

1.68

1.64

1.58

1.68

1.58

1.47

1.46

1.38

1.24

1.13

Waste kt

13,998

14,456

12,640

9,088

7,663

6,489

5,488

4,966

4,036

3,235

2,648

2,704

5,032

82

Table 18.4 50,000 Tonnes per Day Production Schedule

Period (year)

-1

1

2

3

4

5

6

7

8

9

10

 

Mill kt

0

9,125

9,125

9,125

9,125

9,125

18,250

18,250

18,250

18,250

18,250

 

Cu grade %

0.000

0.852

0.765

0.729

0.633

0.599

0.594

0.578

0.624

0.676

0.621

 

Au grade g/t

0.176

0.219

0.240

0.252

0.230

0.221

0.184

0.212

0.203

0.218

0.200

 

Ag grade g/t

1.521

1.881

1.630

1.676

2.093

1.929

1.807

1.436

1.550

1.715

1.604

 

Waste kt

5,000

11,341

6,189

15,811

18,250

18,935

20,037

19,919

4,755

40,159

21,225

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Period (year)

11

12

13

14

15

16

17

18

19

20

21

22

Mill kt

18,250

18,250

18,250

18,250

18,250

18,250

18,250

18,250

18,250

18,250

18,250

9,343

Cu grade %

0.594

0.608

0.635

0.500

0.555

0.589

0.603

0.623

0.617

0.624

0.610

0.579

Au grade g/t

0.170

0.194

0.187

0.183

0.205

0.198

0.183

0.178

0.185

0.196

0.179

0.126

Ag grade g/t

1.784

1.601

1.551

1.145

1.231

1.318

1.566

1.661

1.633

1.526

1.417

1.236

Waste kt

40,250

55,021

55,021

33,021

33,963

28,454

21,728

14,153

10,453

7,271

5,356

5,109

18.4     Economic Model

Corriente developed an economic model from the AMEC economic model used in their feasibility study. While MDA did not take part in creating the model, MDA did review the model and input values. The calculations were consistent between the Corriente model and the AMEC feasibility model and the input costs were the same with the exception of metals prices and capital costs. The most significant differences were the production schedules; Corriente used the schedules in Table 18.3 and Table 18.4 which have longer mine lives than the feasibility schedule. The inputs are summarized in Table 18.5 and results are shown in Table 18.6 and Table 18.7.

 

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December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 122
 

Table 18.5 Economic Model Inputs

Base Case

Corriente

 

AMEC

Item

 

Value

 

Value

Cu price US$/lb

$

1.10

$

1.00

Au price US$/oz

$

425

$

400

Ag price US$/oz

$

6.50

$

6.50

 

 

 

 

 

Cu mill recov

 

91%

 

91%

Au mill recov

 

47%

 

47%

Processing cost US$/t (LOM)

$

2.96

$

2.87

G&A cost US$/t (LOM)

$

0.64

$

0.64

Mining cost US$/t (LOM)

$

1.14

$

1.14

 

 

 

 

 

Concentrate Grade

 

29.9%

 

29.8%

Moisture

 

8.0%

 

8.0%

Land Conc freight (US$/wmt)

 

$35.82

 

$35.82

Port Charges (US$/wmt)

 

$2.00

 

$1.70

Ocean freight (US$/wmt)

 

$42

 

$42

Total freight charges (US$/wmt)

 

$80

 

$79.52

Con Treatment Charge US$/dmt

 

$75

 

$75

Cu refining Charge US$/pay lb

 

$0.075

 

$0.075

Cu pay factor

 

96.5%

 

96.5%

Cu Unit Deduction

 

1.0%

 

1.0%

Au pay factor

 

95.0%

 

95.0%

Au unit deduction

 

0.0

 

0.0

Au Refining Charge US$/troy oz

 

$6.00

 

$6.00

Ag pay factor

 

90.0%

 

90.0%

Ag unit deduction

 

0.0

 

0.0

Ag Refining Charge US$/troy oz

 

$0.40

 

$0.40

 

 

 

 

 

Concentrate Losses

 

0.25%

 

0.25%

Table 18.6 Economic Model Results, 25,000 tpd Case (8% discount rate)

 

Cu Price

Pre-tax

Pre-tax NPV

 

US$/lb

IRR %

US$ millions

$

1.00

15.8%

111

$

1.10

22.6%

224

$

1.20

28.8%

337

$

1.45

43.1%

620
       

Cu Price

 

Cash Flow (US$ 000's)

 

US$/lb

Year 1

Year 2

Year 3

Year 4

Total

$

1.00

44,598

55,733

42,819

29,079

172,229

$

1.10

56,947

69,326

55,634

40,937

222,844

$

1.45

100,171

116,899

100,486

80,009

397,565

$

1.75

137,220

157,677

138,931

113,961

547,789

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 123
 

Table 18.7 Economic Model Results, 50,000 tpd Case (8% discount rate)

 

Cu Price

Pre-tax

Pre-tax NPV

 

US$/lb

IRR %

US$ millions

$

1.10

24.0%

349

Based on a study by Merit Consultants International Inc., which is part of the AMEC feasibility study, Corriente estimated initial capital to be US$195 million for the 25,000 tpd scenario and US$295 million for the 50,000 tpd scenario. The 50,000 tpd case sees a doubling of plant production capacity in year 5 at an additional capital cost of US$100 million, incurred in year 5. Table 18.8 is a summary of initial capital for the 25,000 tpd case (the 50,000 tpd case is the same except for the additional US$100 million capital spent in year 5).

Table 18.8 25,000 tpd Case Initial Capital

Area

Cost (US$ x1000)

Direct Costs

 

Mine

$11,108

Process Plant

$87,922

Utilities

$6,920

Site Preparation and Roads

$13,561

Tailings

$8,474

Ancillary Facilities

$3,847

Total Direct Costs

$131,832

Indirect Costs

 

Project Indirects

$39,362

Owner Indirects (includes BHP royalty buyout)

$6,376

Total Indirect Costs

$45,738

Subtotal

$177,570

Contingency

$17,735

Total Project

$195,305

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 124
 

19.0     REQUIREMENTS FOR TECHNICAL REPORTS ON PRODUCTION AND DEVELOPMENT PROPERTIES

AMEC Americas Ltd completed a feasibility study on the Mirador property titled "Mirador Copper Project Feasibility Study Report" in May 2005. Corriente filed that study on the SEDAR website on May 13, 2005, and the study is available on the Corriente website, http://www.corriente.com. MDA reviewed sections of the feasibility relating to mining and mining-related economics and believes the information provided to be reasonable and generally current. The work described in Section 18 of this report was based on information from this AMEC feasibility study.

Excerpts from the feasibility are provided below. Note that the terms "ore", "orebody" and "ore body" used by AMEC in the following are not 43-101 compliant terms in that no reserve has been stated for this deposit.

The feasibility study is based on conventional open pit mining of the porphyry copper deposit. The deposit is covered by an average 22 m depth of overburden and a leached cap, a portion of which must be pre-stripped to access the orebody. The sulphide ore body is relatively homogenous, consisting dominantly of primary copper sulphides and is open at depth. Secondary enrichment is thinly developed in places over the primary sulphide mineralization. Overall, the metallurgy is regarded as relatively simple.

The mine plan is based on a contract mining company providing ore to a conventional copper concentrator to support an average milling rate of 25,000 t/d (9.125 Mt/a). All facilities are designed for this throughput and operate on a continuous basis, 24 h/d, 365 d/a.

Run-of-mine ore will be crushed in a gyratory crusher. The mill flow sheet selected for Mirador will be a conventional copper-gold porphyry flowsheet, with relatively coarse primary semi-autogenous and ball mill grinding to about 150 ﾊm followed by copper rougher flotation, concentrate regrind to 30 ﾊm, and cleaner flotation and dewatering. Concentrates produced are predicted to average 29.8% copper at a recovery of 91%. Gold recovery is expected to average 47%. A laboratory analysis of concentrates indicated that no significant deleterious penalty element impurities are present. The concentrate will be trucked via the existing road network in the area to a port facility in Machala for shipment to smelters. Tailings from the process will be impounded in a zero discharge tailings pond; water will be reclaimed from the tailings pond and reused in the process.

The major infrastructure required to develop the property includes road access upgrades, a run-of-river hydroelectric scheme, and power line. The hydroelectric development is not part of the scope of this study and the supply of power will be through an independent build-own-operate arrangement. A 2.7 km access road is needed to connect the plant and administration areas to the existing highway that passes by the property. Access between the plant area and the mine will be via upgraded existing roads including a new 5 km section to the pit area. A 10 km overland conveyor will connect the process plant and the crusher. In addition, a 100 km power line will have to be constructed, as part of the Sabanilla Hydroelectric Project, to connect the site to the hydroelectric power station and the existing power grid. The power demand of the project is about 28.3 MW. Seasonal variations in the output of the hydroelectric scheme result in an average output of about 23.5 MW and, on average, 4.8 MW of supplementary power will be imported from the existing power grid. [Note the update to the power situation described in Section 5.4.]

 

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December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
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Page 125
 

Merit Consultants International Inc. (Merit) estimated the capital cost to build the facilities as described in this report to be US$202 million. Mining costs were based on contract mining budget quotations. Process operating costs and G&A costs were estimated by AMEC with input from Corriente.

Mining at Mirador will be by conventional open pit truck and shovel methods. Budget pricing was obtained for contract mining. The mining fleet is estimated to consist of two 19.9 m3 front-end loaders and eight 140 t trucks. Support equipment will include bulldozers, graders, and excavators to maintain the surfaces of the roads, dumps and operating benches and the water collection system at the pit rim and in-pit.

The parameters used in the detailed pit design, including the geotechnical data described above, are as follows:

The current electrical power situation is described in Section 5.4.

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 126
 

20.0     CONCLUSIONS

The last NI 43-101 compliant Technical Report for the Mirador project was prepared by MDA and was filed on SEDAR in May 2006. Since that time, Corriente Resources Inc has advanced knowledge of the Mirador Project mineral resources by completing:

In addition to the work noted above, the following Mirador Project programs are ongoing:

This Technical Report provides a summary of all work conducted at Mirador and Mirador Norte since the inception of the Mirador Project, and an update and review of the Mirador Project activities that took place subsequent to the filing of the last Technical Report. MDA has reviewed the methodology and results of the 2006 drilling program at Mirador Norte. This program included drill holes MN30 to MN68. The updated Mirador Norte drill hole assay database contains 4,238 copper assays and 4,233 gold assays in 68 holes. For the 2006 drilling program, as for the 2005 Mirador drilling, Corriente generally followed the quality assurance/quality control (QA/QC) guidelines recommended by AMEC Americas Ltd (AMEC, 2004). MDA has reviewed the results of Corriente's 2005 QA/QC program for the Mirador deposit drilling program, but did not take independent samples from the 2005 Mirador deposit drill holes. However, MDA did take check samples from drilling conducted prior to 2005 at the Mirador deposit. MDA has also reviewed the results of Corriente's 2003-2004 and 2006 QA/QC programs for the Mirador Norte deposit drill campaigns, and also took 17 check samples of split (quartered) drill core from Mirador Norte. The discussion in the following section relates to both the 2005 Mirador and 2006 Mirador Norte drilling programs.

The sample preparation procedures from the 2005 Mirador drilling program and the 2003-2006 Mirador Norte programs are appropriate and well done, and the assays and analyses are of good quality. Based on the results of the assays and analyses of standard samples inserted into the sample streams, there does not appear to be any significant bias in the assay or analytical data. The results from the inserted blank samples indicate that the sample preparation procedures are conducted with appropriate care. Copper analyses of pulp duplicates from the Mirador and Mirador Norte deposits reproduce well, while gold fire assays of pulp duplicates show modest variability. MDA and Sivertz also recommend that a small percentage of samples be sent "blind" to a second umpire laboratory, as an additional check on the primary laboratory.

 

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December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 127
 

In May 2006, MDA reported a resource update for the Mirador deposit based on the 52 additional 2005 drill holes. MDA reported Measured and Indicated resources of 437,670,000 tonnes grading 0.61% Cu, 190 ppb gold, and 1.5 ppm silver at a 0.40% Cu cutoff grade. Inferred resources, also at a 0.40% Cu cutoff, were reported to be 235,400,000 tonnes grading 0.52% Cu, 170 ppb gold, and 1.3 ppm silver.

MDA completed a resource estimate in September 2006 for Mirador Norte; this is the first NI 43-101 compliant resource estimate made for this deposit. MDA reported Indicated resources of 171,410,000 tonnes grading 0.51% Cu and 89 ppb gold at a 0.40% Cu cutoff grade, and Inferred resources of 44,820,000 tonnes grading 0.51% Cu and 68 ppb Au, also at a 0.40% Cu cutoff.

The Mirador deposits present a unique situation for sampling. The distinctly low RQD material makes it more difficult to obtain higher core recovery and presents the opportunity to introduce bias. A study of Mirador drill results suggests that in spite of the low RQD, the grade to core recovery relationship is due more to geology than to sampling bias; the same holds true for Mirador Norte. Post-mineral weathering is a more important geologic characteristic than fracturing in relating the grade and rock quality.

 

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 128
 

21.0     RECOMMENDATIONS

MDA and Sivertz believe that Mirador is a property of merit. For the Mirador Norte deposit specifically, it is recommended that certain work be completed:

The cost of this work would be approximately US$150,000, excluding drilling costs which could add approximately US$250,000. In addition, core drilling should continue, to upgrade the resource classification and facilitate evaluation of the resource as well as to test the model.

For the Mirador deposit:

The ongoing engineering, cost estimation, and environmental/social baseline work should be completed, to support the bankable Feasibility Study currently being prepared by SNC-Lavalin. As of the effective date of this report, this work is all underway; it will be reported in the SNC-Lavalin BFS:

Estimated costs for the previously described engineering work would be approximately $150,000. An estimate of costs for the full range of Feasibility Study engineering and construction work is beyond the scope of this report. Corriente reports that it has budgeted approximately $15.2 million for Engineering, Procurement, Construction and Management ("EPCM") through the end of 2008.

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 129
 

22.0     DATE AND SIGNATURE PAGE

Effective Date of report:

October 19, 2006

The information upon which the contained resource estimates are based was current as of the Effective Date of October 19, 2006; for the land data in this report, the Effective Date is November 11, 2006.

Completion Date of report: November 30, 2006
   
"George Sivertz"                   
George Sivertz, P. Geo.   Date Signed: November 30, 2006
     
"Steve Ristorcelli"                 
Steven Ristorcelli, P. Geo.   Date Signed: November 30, 2006
     
"Scott Hardy"                    
Scott Hardy, P. Eng.   Date Signed: November 30, 2006
     
"John Hoffert"                    
John R. Hoffert, P.Eng.   Date Signed: November 30, 2006

 

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 130
 

23.0     REFERENCES

AMEC Americas Limited, 2005: Mirador Copper Project Feasibility Study Report. May 2005.

AMEC Americas Limited, 2004: Technical Report, Mirador Project. Morona Santiago Province, Ecuador. AMEC Americas Limited Technical Report prepared for Corriente Resources Inc, October 22, 2004.

Corriente Resources Inc, 2005: Environmental Impact Assessment for Mirador Project Submitted to the Ecuador Government. News Release dated December 20, 2005.

Corriente Resources Inc, 2005: Mirador Mine Life Extended to 38 Years with New Optimization Results for Starter Copper Project. News Release dated November 17 2005.

Corriente Resources Inc, 2005: Optimization Drilling Completed at Mirador Project. News Release dated August 8, 2005

Corriente Resources Inc, 2005: High Grade Copper Intersected at Mirador Project. News Release dated July 6, 2005.

Corriente Resources Inc, 2005: Optimization Well Underway at Mirador Project, Ecuador. News Release dated May 19, 2005.

Corriente Resources Inc, 2005: Positive Feasibility Study Completed on Mirador Copper-Gold Starter Project, Southeast Ecuador. News Release dated April 14, 2005.

Dawson, J.M., and Makepeace, D.K, 2003: Mirador Project, Corriente Copper Belt, Southeast Ecuador. Order-of-Magnitude Study, Part 1, Technical Report. February 2003.

Drobe, J., 2006: Personal Communications with George Sivertz, P.Geo.

Drobe, J., 2006: Internal Memorandum to Corriente Resources Inc.

EcuaCorriente, 2006: Internal Memorandum to Corriente Resources Inc., dated October 6, 2006.

Makepeace, D.K, 2001: Corriente Copper Belt Project, Southeast Ecuador, Order-of-Magnitude Study (Preliminary Assessment Technical Report), June 22, 2001.

Makepeace, D.K, 2002: Mirador Project, Corriente Copper Belt, Southeast Ecuador. Preliminary Assessment Technical Report, February 12, 2002.

Makepeace, D.K, 2002: Mirador Project, Corriente Copper Belt, Southeast Ecuador. Preliminary Assessment Technical Report, September 3, 2002.

Mine Development Associates, 2005: Update on Copper, Gold and Silver Resources and Pit Optimizations, Mirador Project, Ecuador. December 6, 2005.

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 131
 

Mine Development Associates, 2006: Technical Report Update on the Copper, Gold and Silver Resources and Pit Optimizations, Mirador Project, Ecuador. May 18, 2006.

P&T Asesores Legales, Abogados 2006: Letter Regarding Certain Corporate Matters and the Status of Title to the Mining Concessions in Ecuador. Prepared for Corriente Resources Inc, May 25 2006.

Trejo Rodriguez & Asociados, Abogados 2006: Letter Report Regarding the Mirador Property.  Prepared for Corriente Resources Inc, October 19, 2006.

www.aurelian.ca: October 16 2006.

 

 

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 132
 

24.0     AUTHOR'S CERTIFICATE AND SIGNATURE PAGE

I, Steven Ristorcelli, P. Geo., do hereby certify that:

1.         I am currently employed as Principal Geologist by:

                    Mine Development Associates, Inc.
                    210 South Rock Blvd.
                    Reno, Nevada 89502.

2.         I graduated with a Bachelor of Science degree in Geology from Colorado State University in 1977 and a Master of Science degree in Geology from the University of New Mexico in 1980.

3.         I am a Professional Geologist in the states of California (#3964) and Wyoming (#153) and a Certified Professional Geologist (#10257) with the American Institute of Professional Geologists, and a member of the Geological Society of Nevada, Society for Mining, Metallurgy, and Exploration, Inc., and Prospectors and Developers Association of Canada.

4.         I have worked as a geologist for a total of 28 years since my graduation from undergraduate university.

5.         I have read the definition of "qualified person" set out in National Instrument 43-101 ("NI 43-101") and certify that by reason of my education, affiliation with a professional association (as defined in NI 43-101) and past relevant work experience, I fulfill the requirements to be a "qualified person" for the purposes of NI 43-101.

6.         I am responsible for or was involved with the preparation of this technical report titled "Technical Report Update on the Copper, Gold, and Silver Resources and Pit Optimizations: Mirador and Mirador Norte Deposits, Mirador Project, Ecuador" for Corriente Resources Inc. November 30 2006. I visited the project during the period January 4 to January 7, 2005 and again from August 31 to September 2, 2006.

7.         I have had no prior involvement with the property or project.

8.         I am not aware of any material fact or material change with respect to the subject matter of the Technical Report that is not reflected in the Technical Report, the omission to disclose which makes the Technical Report misleading.

9.         I am independent of the issuer applying all of the tests in section 1.5 of National Instrument 43-101.

10.       I have read National Instrument 43-101 and Form 43-101F1, and the Technical Report has been prepared in compliance with that instrument and form.

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 133
 

11.         I consent to the filing of the Technical Report with any securities regulatory authority, stock exchange and other regulatory authority and any publication by them, including electronic publication of the Technical Report in the public company files on their websites accessible by the public.

Dated this 30th day of November, 2006.

 

"Steven Ristorcelli"                             
Signature of Qualified Person

Steven Ristorcelli                                    
Print Name of Qualified Person

 

 

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 134
 

I, George Sivertz, residing at 11708-246th Street, Maple Ridge, BC, V4R 1K8, do hereby certify that:

1.         I am currently employed as Senior Geologist by:

                    OreQuest Consultants Ltd.
                    #306 – 595 Howe Street
                    Vancouver BC, Canada V6C 2T5

2.         I hold a B.Sc. (Honours) degree in Geological Science granted by the University of British Columbia in 1976.

3.         I have been a registered member in good standing of the Association of Professional Engineers and Geoscientists of British Columbia since 1992.

4.         I am a professional geologist and have practiced my profession on a full time basis in Canada, the USA, Europe, Asia, and South America since 1978.

5.         I have read the definitions of "Qualified Person" set out in NI 43-101 and certify that by reason of my education, affiliation with a professional association (as defined in NI 43-101) and relevant work experience, I fulfil the requirements to be a "Qualified Person" for the purposes of NI 43-101.

6.         I am responsible for or was involved with the preparation of all parts of this technical report titled "Technical Report Update on the Copper, Gold, and Silver Resources and Pit Optimizations: Mirador and Mirador Norte Deposits, Mirador Project, Ecuador" for Corriente Resources Inc. November 30, 2006. MDA is the primary author of Sections 16 and 17.

7.         I visited the Mirador property several times between October 24th and October 30th, 2006.

8.         I have no direct involvement with, and do not expect to have any direct involvement with Corriente Resources Inc., or any of its subsidiary companies located in Canada, Ecuador or elsewhere.

9.         As of the date of this certificate, to the best of my knowledge and belief, the parts of the Sections of this Technical Report for which I am responsible contain all scientific and technical information that is required to be disclosed to ensure that the Technical Report is not misleading.

10.         I am independent of Corriente Resources Inc., applying all the tests in Section 1.4 of NI 43-101 and Section 3.5 of NI 43-101 Companion Policy.

11.         I have read NI 43-101 and NI 43-101F1 and the technical report has been prepared in compliance with that instrument and form.

12.        I consent to the filing of the Technical Report with any securities regulatory authority, stock exchange and other regulatory authority and any publication by them, including electronic publication of the Technical Report in the public company files in websites accessible by the public.

Dated this 30th day of November, 2006.

"George Sivertz"                                       
Signature of Qualified Person

George Sivertz                                            
Print Name of Qualified Person

 

Mine Development Associates  
December 11, 2006  

Technical Report Update on the Copper, Gold, and Silver Resources and Reserves
Corriente Resources
 

Page 135
 

I, Scott Hardy, P. Eng., do hereby certify that:

1.         I am currently employed as Senior Engineer by:

Mine Development Associates, Inc.
210 South Rock Blvd.
Reno, Nevada 89502.

2.         I graduated with a Bachelor of Science degree in General Engineering from Oregon State University in 1978 and Bachelor of Science degree in Geology from the University of Wyoming in 1984.

3.         I am a Registered Professional Engineer in the state of Nevada (#11891) and a member of the Society for Mining, Metallurgy, and Exploration, Inc.

4.         I have worked as an engineer for a total of 19 years since my graduation from undergraduate university.

5.         I have read the definition of "qualified person" set out in National Instrument 43-101 ("NI 43-101") and certify that by reason of my education, affiliation with a professional association (as defined in NI 43-101) and past relevant work experience, I fulfill the requirements to be a "qualified person" for the purposes of NI 43-101.

6.         I am responsible for or was involved with the preparation of this technical report titled "Technical Report Update on the Copper, Gold, and Silver Resources and Pit Optimizations: Mirador and Mirador Norte Deposits, Mirador Project, Ecuador" for Corriente Resources Inc. November 30, 2006. I have not visited the Mirador property.

7.         I have had no prior involvement with the property or project.

8.         I am not aware of any material fact or material change with respect to the subject matter of the Technical Report that is not reflected in the Technical Report, the omission to disclose which makes the Technical Report misleading.

9.         I am independent of the issuer applying all of the tests in section 1.5 of National Instrument 43-101.

10.       I have read National Instrument 43-101 and Form 43-101F1, and the Technical Report has been prepared in compliance with that instrument and form.

11.       I consent to the filing of the Technical Report with any securities regulatory authority, stock exchange and other regulatory authority and any publication by them, including electronic publication of the Technical Report in the public company files on their websites accessible by the public.

Dated this 30th day of November, 2006.

"Scott Hardy"                                            
Signature of Qualified Person

Scott Hardy                                                
Print Name of Qualified Person

 

Mine Development Associates  
December 11, 2006  

 

Appendix A

Letter Report Regarding the Mirador Property
by Trejo Rodriguez & Asociados, Abogados

 

 

 

TREJO RODRIGUEZ & ASSOCIATES
ABOGADOS

Quito, October 19, 2006

Messrs.
ECUACORRIENTE S.A.
QUITO

Attn: Dr. Mauricio Nunez

Dear sirs:

In reference with the requested legal opinions the status of title to the mining concessions in Ecuador, we have reviewed the corporate records of ECUACORRIENTE S.A. and such other documents and considered such matters of law as we have considered necessary.

Based on our review, we consider that:

1.     The National Direction of Mining (DINAMI), has issued up to the present, in favour of ECUACORRIENTE S.A. 7 mining concessions titles in reference with the following denominated areas:

AREA NAME

 HECTARES STATUS

PATENTS PAYMENTS

 

    

 

CURIGEM 18

 1,600 has. TITLE REGISTERED

USD $ 3.200,00

CURIGEM 18 E

 800 has. TITLE REGISTERED

USD $ 1.600,00

CURIGEM 19

 2,900 has. TITLE REGISTERED

USD $ 5.800,00

MIRADOR 1

 2,400 has. TITLE REGISTERED

USD $ 4.800,00

MIRADOR 2

 1,200 has. TITLE REGISTERED

USD $ 2.400,00

MIRADOR 3

 1,020 has. TITLE REGISTERED

USD $ 1.020,00

MIRADOR 4

 8 has. TITLE REGISTERED

USD $ 8,00

2.     Based on a review of the Mining Title for each mining concession issued by the National Mining Office, which is a department of the Ministry of Energy and Mines in charge of managing the processes of issuance, conservation and extinction of mining rights in accordance with the current mining laws and regulations of Ecuador (the "Mining Law"), each of the properties, is duly registered in the name of ECUACORRIENTE S.A.

3.     All legal and financing and legal obligations are compiled and up to date; therefore, the above mentioned titles are in force.

The next mining patents payments ends march 31, 2007.

_________________________________________
Ave. Oreliana E11 - 28 y Coruna Esq., Efificio Oreliana, Piso 5, Oficina 502
Telefonos: (593 2) 255 - 6367/252 - 2=7575
Quito - Ecuador

TREJO RODRIGUEZ & ASOCIADOS
ABOGADOS

4. In regards to the status of Tile of the mining concessions, each of the Properties is in good standing until the date of expiration of regiestration.

Please do not hesitate to contact me if you have any other inquires or doubts.

Best Regards,

Dr. Juan Xavier Trejo
ATTORNEY AT LAW

 

Appendix B

Mirador and Mirador Norte Drill Hole Locations, Orientations and Lengths

 

 

Hole East North Elev. Depth Azimuth Dip
             
M01 784,429.1 9,604,229.0 1,335.9 104.6 180 -70
             
M02 784,548.1 9,604,336.8 1,230.6 198.2 90 -90
             
M03 785,225.5 9,604,083.8 1,389.8 368.8 360 -90
             
M04 784,533.4 9,604,095.9 1,345.2 92.4 90 -90
             
M05 784,728.7 9,604,200.7 1,363.9 226.4 90 -90
             
M06 784,734.1 9,604,104.1 1,369.3 199.6 90 -90
             
M07 784,731.2 9,603,996.8 1,418.7 104.4 90 -90
             
M08 784,847.0 9,604,315.5 1,296.3 158.2 90 -90
             
M09 784,837.3 9,604,099.4 1,408.6 150.3 90 -90
             
M10 784,821.5 9,603,899.3 1,408.0 164.0 90 -90
             
M11 784,954.0 9,604,295.8 1,312.6 150.9 90 -90
             
M12 784,923.8 9,604,105.5 1,391.7 211.2 90 -90
             
M13 784,912.1 9,603,788.6 1,459.9 153.0 90 -90
             
M14 785,031.8 9,604,294.3 1,327.4 150.9 90 -90
             
M15 785,030.2 9,603,974.8 1,386.0 176.2 90 -90
             
M16 785,022.8 9,603,887.7 1,385.6 214.0 90 -90
             
M17 785,158.2 9,604,410.3 1,304.3 131.1 90 -90
             
M18 785,175.5 9,604,299.3 1,298.2 86.3 90 -90
             
M19 785,168.6 9,604,192.6 1,319.0 106.1 90 -90
             
M20 785,134.5 9,604,084.6 1,356.4 244.8 90 -90
             
M21 785,254.5 9,604,493.8 1,243.9 54.9 90 -90
             
M22 784,551.2 9,603,892.8 1,507.7 128.0 90 -90
             
M23 785,342.0 9,604,280.1 1,339.2 400.8 360 -90
             
M24 784,515.0 9,604,112.0 1,345.4 69.7 260 -60
             
M25 784,429.1 9,604,229.0 1,335.9 223.4 255 -60
             
M26 785,106.6 9,603,790.8 1,464.0 99.2 90 -90
             
M27 785,332.8 9,604,204.0 1,370.2 438.9 270 -70
             
M28 785,333.9 9,604,093.7 1,325.8 258.5 135 -70

Hole East North Elev. Depth Azimuth Dip
             
M29 785,209.7 9,603,890.7 1,385.1 457.2 360 -90
             
M30 785,124.3 9,603,976.4 1,419.8 175.3 90 -90
             
M31 784,934.0 9,603,982.0 1,360.7 279.5 90 -90
             
M32 785,219.9 9,603,983.5 1,361.2 295.4 90 -90
             
M33 784,932.0 9,604,200.8 1,378.0 285.6 90 -90
             
M34 785,109.6 9,603,791.7 1,464.0 429.8 115 -70
             
M35 784,920.8 9,603,890.9 1,414.4 301.8 90 -90
             
M36 785,121.4 9,603,884.6 1,451.5 175.3 90 -90
             
M37 785,335.8 9,603,867.2 1,354.1 400.0 360 -90
             
M38 785,002.5 9,603,680.1 1,498.1 486.2 360 -90
             
M39 785,206.5 9,603,683.7 1,410.0 272.5 135 -70
             
M40 785,205.9 9,603,684.1 1,410.0 298.7 360 -90
             
M41 785,040.5 9,604,081.1 1,311.8 249.9 90 -90
             
M42 785,025.3 9,604,190.3 1,330.4 294.1 90 -90
             
M43 784,903.6 9,603,679.9 1,539.6 399.3 360 -90
             
M44 784,928.1 9,603,935.7 1,391.9 419.1 360 -90
             
M45 784,932.9 9,604,038.7 1,364.0 303.3 360 -90
             
M46 784,822.8 9,604,005.8 1,421.0 408.1 360 -90
             
M47 784,722.4 9,603,901.2 1,474.6 349.0 360 -90
             
M48 784,840.2 9,604,197.6 1,371.3 448.1 360 -90
             
M49 784,747.3 9,604,313.6 1,356.8 492.3 360 -90
             
M50 784,551.0 9,604,431.7 1,205.7 341.1 360 -90
             
M51 784,760.6 9,604,409.4 1,356.1 449.6 360 -90
             
M52 784,956.3 9,604,395.4 1,290.1 443.5 360 -90
             
M53 784,734.7 9,604,495.5 1,291.1 198.4 360 -90
             
M54 784,842.4 9,604,500.8 1,335.5 188.7 360 -90
             
M55 784,932.3 9,604,490.5 1,316.2 363.0 360 -90
             
M56 785,020.6 9,604,511.3 1,240.1 399.9 360 -90

Hole East North Elev. Depth Azimuth Dip
             
M57 785,015.7 9,604,618.6 1,239.0 250.9 360 -90
             
M58 785,139.7 9,604,521.8 1,268.0 180.8 360 -90
             
M59 784,849.1 9,604,420.8 1,355.4 391.7 360 -90
             
M60 784,667.3 9,604,304.3 1,341.8 410.3 360 -90
             
M61 784,907.0 9,604,580.2 1,307.0 171.9 360 -90
             
M62 784,255.9 9,604,470.0 1,310.0 183.3 105 -60
             
M63 784,705.6 9,604,400.2 1,338.2 400.5 90 -60
             
M64 784,811.1 9,604,404.5 1,356.8 400.8 110 -60
             
M65 784,759.4 9,604,359.3 1,362.3 300.2 0 -90
             
M66 784,844.6 9,604,362.9 1,327.8 300.2 0 -90
             
M67 784,898.9 9,604,301.3 1,291.1 300.2 0 -90
             
M68 784,995.2 9,604,298.9 1,313.1 315.5 90 -85
             
M69 785,098.7 9,604,299.1 1,265.1 269.8 110 -80
             
M70 785,077.3 9,604,400.1 1,238.2 249.9 0 -90
             
M71 785,100.1 9,604,197.1 1,284.1 300.2 110 -80
             
M72 785,157.4 9,604,413.6 1,304.4 286.5 0 -90
             
M73 785,250.6 9,604,297.5 1,342.5 189.0 0 -90
             
M74 785,074.2 9,603,972.5 1,390.4 288.0 270 -85
             
M74A 785,074.3 9,603,972.6 1,390.4 73.2 0 -90
             
M75 784,923.0 9,604,104.2 1,391.8 300.3 135 -60
             
M76 784,657.3 9,604,004.1 1,442.1 254.5 189 -89
             
M77 784,841.1 9,604,197.3 1,371.3 300.3 135 -60
             
M78 784,736.5 9,604,104.8 1,369.0 300.3 90 -55
             
M79 784,662.6 9,604,110.4 1,409.8 269.8 0 -90
             
M80 784,749.3 9,604,313.2 1,356.7 300.2 135 -60
             
M81 784,777.7 9,603,903.2 1,433.0 256.0 0 -90
             
M82 784,734.5 9,604,495.6 1,291.1 225.6 90 -65
             
M83 785,139.4 9,604,608.4 1,222.3 150.9 0 -90

Hole East North Elev. Depth Azimuth Dip
             
M84 784,553.8 9,604,242.2 1,261.2 249.9 0 -90
             
M85 784,922.8 9,604,104.8 1,391.4 300.2 225 -60
             
M86 785,040.9 9,604,080.7 1,311.8 202.7 135 -60
             
M87 784,633.5 9,604,208.7 1,351.8 300.2 225 -70
             
M88 784,680.8 9,604,392.1 1,324.0 349.9 315 -80
             
M89 785,098.7 9,604,300.0 1,265.3 358.1 45 -60
             
M90 785,224.9 9,604,082.7 1,389.3 298.7 135 -60
             
M91 784,909.8 9,604,640.0 1,291.2 261.5 0 -90
             
M92 784,839.5 9,604,567.0 1,291.3 290.2 0 -90
             
M93 784,639.0 9,604,473.2 1,253.8 249.9 140 -72
             
M94 784,999.2 9,604,557.5 1,253.4 201.2 0 -90
             
M95 785,104.2 9,604,467.3 1,258.2 249.9 0 -90
             
M96 785,165.1 9,604,491.9 1,277.5 249.9 180 -70
             
M97 785,251.0 9,604,297.4 1,342.4 342.3 105 -75
             
M98 785,215.4 9,604,406.4 1,295.8 251.5 140 -75
             
M99 785,311.6 9,604,346.3 1,291.1 249.9 0 -90
             
M100 785,358.5 9,604,218.9 1,351.1 201.2 0 -90
             
M101 785,259.8 9,604,138.3 1,385.2 278.6 0 -90
             
M102 785,219.5 9,603,983.3 1,361.0 249.9 270 -75
             
M103 785,022.2 9,603,887.5 1,385.4 247.5 90 -65
             
M104 785,017.2 9,603,846.6 1,403.5 209.1 120 -72
             
M105 784,972.2 9,604,184.2 1,362.8 424.0 135 -80
             
M106 784,976.3 9,604,230.8 1,336.5 417.6 270 -85
             
M107 785,000.3 9,603,763.7 1,458.4 249.9 90 -75
             
M108 785,260.5 9,604,138.2 1,385.1 196.6 135 -70
             
M109 785,092.2 9,603,709.3 1,464.3 177.7 90 -75
             
M110 784,820.8 9,603,709.1 1,534.8 230.1 90 -77
             
M111 784,813.1 9,603,784.8 1,462.3 179.5 135 -70
             
M112 784,699.5 9,603,858.2 1,475.1 231.3 135 -70

Hole East North Elev. Depth Azimuth Dip
             
M113 784,652.3 9,603,906.3 1,482.3 250.2 0 -90
             
M114 784,614.8 9,603,950.1 1,461.8 242.3 270 -80
             
M115 784,610.7 9,604,022.8 1,413.4 201.2 220 -85
             
M116 784,694.0 9,604,262.4 1,362.1 431.3 310 -75
             
M117 784,589.4 9,604,122.1 1,354.8 135.7 160 -72
             
M118 784,394.8 9,604,279.3 1,327.8 150.9 0 -90
             
M119 784,482.8 9,604,293.3 1,271.4 170.7 0 -90
             
M120 784,839.2 9,604,567.7 1,291.4 161.2 335 -70
             
M121 785,139.3 9,604,521.7 1,267.7 254.8 260 -70
             
M122 784,901.9 9,604,542.2 1,319.1 249.9 0 -90
             
M123 784,801.9 9,604,503.1 1,306.7 225.6 90 -65
             
M124 784,735.2 9,604,494.9 1,291.2 231.0 135 -65
             
M125 784,959.9 9,604,459.9 1,306.0 286.5 90 -70
             
M126 784,878.9 9,604,460.2 1,343.8 285.0 90 -70
             
M127 784,674.9 9,604,361.2 1,332.7 251.5 90 -70
             
M128 784,616.1 9,604,405.6 1,255.4 100.9 0 -90
             
M129 784,599.4 9,604,342.5 1,267.7 216.7 135 -80
             
M130 784,568.0 9,604,288.6 1,264.9 120.4 0 -90
             
M131 784,553.6 9,604,242.3 1,260.9 225.9 270 -70
             
M132 784,545.6 9,604,203.5 1,262.3 151.2 180 -75
             
M133 784,554.2 9,604,242.4 1,261.0 201.5 110 -60
             
M134 784,462.1 9,604,171.0 1,337.9 151.2 0 -90
             
M135 784,671.3 9,604,206.8 1,377.1 360.9 0 -90
             
M136 784,743.1 9,604,159.2 1,360.0 195.4 90 -80
             
M137 784,673.1 9,604,156.5 1,400.7 151.2 0 -90
             
M138 784,741.4 9,604,065.4 1,378.9 250.2 90 -80
             
M139 785,051.8 9,604,267.2 1,321.6 94.8 135 -70
             
M139A 785,051.8 9,604,267.2 1,321.6 96.3 135 -70
             
M140 784,847.7 9,604,288.5 1,297.4 250.2 135 -70
             
M141 785,020.4 9,604,407.7 1,257.6 201.2 140 -70

Hole East North Elev. Depth Azimuth Dip
             
MN01 783,456.4 9,606,809.6 932.4 298.7 225 -60
             
MN02 783,457.9 9,606,811.1 932.5 164.5 45 -60
             
MN03 782,986.2 9,607,420.0 987.1 298.7 225 -60
             
MN04 782,988.7 9,607,422.5 987.3 250.0 45 -60
             
MN05 783,267.0 9,606,771.9 953.3 300.2 45 -60
             
MN06 783,276.2 9,606,970.5 943.4 300.2 45 -60
             
MN07 783,067.8 9,606,781.2 992.7 294.1 45 -60
             
MN08 783,161.4 9,606,675.7 927.7 300.2 45 -60
             
MN09 783,172.2 9,606,874.3 984.2 324.6 45 -60
             
MN10 783,383.9 9,607,165.5 1,014.8 300.2 225 -60
             
MN11 783,184.3 9,607,171.3 1,032.5 324.6 0 -90
             
MN12 783,077.6 9,606,980.7 1,070.1 298.7 45 -70
             
MN13 782,976.7 9,607,164.1 993.8 137.2 45 -60
             
MN14 783,189.1 9,607,371.5 994.3 213.4 225 -60
             
MN15 783,401.9 9,606,601.3 894.3 239.3 45 -60
             
MN16 783,394.3 9,606,418.7 900.1 249.9 45 -60
             
MN17 783,472.4 9,606,483.4 912.2 242.3 45 -60
             
MN18 783,583.1 9,606,576.9 922.7 230.1 45 -60
             
MN19 783,677.6 9,606,673.3 927.5 214.9 45 -60
             
MN20 783,319.7 9,606,516.4 897.8 239.9 45 -60
             
MN21 783,485.3 9,606,695.8 905.4 249.0 45 -60
             
MN22 783,569.8 9,606,776.9 934.3 234.7 45 -60
             
MN23 783,389.9 9,606,859.2 909.8 249.9 45 -60
             
MN24 783,481.5 9,606,977.4 964.0 236.2 45 -60
             
MN25 783,425.8 9,607,221.6 1,035.3 139.3 0 -90
             
MN25A 783,426.0 9,607,222.0 1,035.3 68.6 45 -60
             
MN26 783,264.3 9,607,250.6 1,016.1 102.0 0 -90
             
MN27 783,330.0 9,607,325.5 979.3 100.6 0 -90
             
MN28 783,249.6 9,607,449.0 955.9 121.9 0 -90
             
MN29 783,152.3 9,607,580.7 947.3 100.6 0 -90

Hole East North Elev. Depth Azimuth Dip
             
MN30 783,749.8 9,606,613.1 938.3 112.8 45 -60
             
MN31 783,814.0 9,606,692.0 977.1 132.6 45 -60
             
MN32 783,740.6 9,606,748.9 995.8 150.4 45 -75
             
MN33 783,817.0 9,606,825.6 1,007.5 68.6 90 -90
             
MN34 783,658.5 9,606,837.7 940.2 159.4 45 -75
             
MN35 783,727.0 9,606,910.7 960.9 88.4 45 -90
             
MN36 783,626.1 9,606,970.8 952.0 54.9 360 -90
             
MN37 783,564.7 9,607,047.5 967.3 109.7 45 -75
             
MN38 783,702.1 9,607,055.0 1,006.6 89.6 45 -90
             
MN39 783,615.2 9,607,152.2 1,010.7 85.3 45 -75
             
MN40 783,766.7 9,607,122.7 1,064.4 91.4 235 -90
             
MN41 783,701.8 9,607,239.2 1,030.5 127.4 90 -90
             
MN42 783,503.9 9,607,295.6 987.7 150.3 235 -90
             
MN43 783,570.7 9,607,373.8 961.6 94.5 45 -75
             
MN44 783,405.4 9,607,391.5 948.0 174.7 235 -65
             
MN45 783,312.5 9,607,526.1 917.6 102.1 235 -65
             
MN46 782,891.7 9,607,319.1 899.0 42.7 0 -90
             
MN47 782,825.5 9,607,022.2 969.2 81.4 180 -90
             
MN48 782,913.2 9,607,088.7 983.7 150.9 90 -90
             
MN49 783,012.3 9,607,040.7 1,048.9 120.4 0 -90
             
MN50 783,094.8 9,607,116.1 1,051.2 115.8 0 -90
             
MN51 783,022.5 9,606,910.3 1,043.6 123.4 45 -90
             
MN52 782,955.6 9,606,835.4 1,004.9 100.6 45 -90
             
MN53 783,156.7 9,607,001.4 1,006.3 85.3 0 -90
             
MN54 783,073.0 9,607,265.0 1,014.9 150.9 0 -90
             
MN55 783,459.2 9,607,095.6 956.2 298.3 0 -90
             
MN56 783,625.0 9,606,969.4 952.0 352.1 225 -72
             
MN57 783,436.9 9,606,637.1 900.4 249.9 135 -70
             
MN58 783,300.8 9,606,674.0 917.2 300.2 0 -90
             
MN59 783,243.5 9,606,599.2 902.6 275.8 90 -75
MN60       233.2 45 -60

Hole East North Elev. Depth Azimuth Dip
  783,245.1 9,606,451.7 892.6      
             
MN61 783,691.1 9,606,557.8 933.9 227.1 45 -60
             
MN62 783,630.4 9,606,486.3 914.9 210.3 45 -60
             
MN63 783,544.8 9,606,416.1 908.9 245.4 45 -60
             
MN64 783,369.7 9,606,730.5 897.9 400.8 45 -75
             
MN65 783,315.0 9,606,919.5 946.0 420.6 90 -80
             
MN66 783,618.6 9,606,716.0 925.8 400.8 270 -85
             
MN67 783,478.6 9,606,344.7 902.4 201.2 45 -70
             
MN68 783,866.5 9,606,613.8 941.6 201.4 0 -90

 

 

 

 

Appendix C

Sample Descriptive Statistics For Copper, Gold, and Silver for Mirador and Mirador Norte

 

 

Zones

Material

1000

Grade

100,200,300

Lithology

10,20

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

6,556

0.600

0.600

0.238

0.40

0.01

1.87

%

ppb Au MDA

6,556

178.000

201.024

124.445

0.62

0.0

3159

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

1000

Grade

0,100,200

Lithology

10,20

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

2,570

0.330

0.353

0.192

0.54

0.01

1.87

%

ppb Au MDA

2,570

116.000

130.913

90.289

0.69

0.0

1079

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

>=1000

Grade

100,200,300

Lithology

10,20

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

7,631

0.580

0.562

0.315

0.56

0.01

3.52

%

ppb Au MDA

7,631

181.000

205.398

126.263

0.61

0.0

3159

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

>=1000

Grade

0,100,200

Lithology

10,20

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

2,957

0.320

0.339

0.219

0.65

0.01

2.24

%

ppb Au MDA

2,957

116.000

133.145

93.606

0.70

0.0

1486

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

1000

Grade

NA

Lithology

30

Early dikes

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

1,196

0.400

0.423

0.223

0.53

0.01

1.65

%

ppb Au MDA

1,196

126.500

150.301

125.547

0.84

3.0

2230

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

all X000s

Grade

NA

Lithology

30

Early dikes

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

1,361

0.400

0.423

0.223

0.53

0.01

1.74

%

ppb Au MDA

1,361

126.500

150.301

125.547

0.84

3.0

2230

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

1000

Grade

NA

Lithology

40

Post-mineral breccia

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

654

0.020

0.062

0.144

2.33

0.00

2.27

%

ppb Au MDA

654

15.000

38.055

117.516

3.09

0.0

2428

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

all X000s

Grade

NA

Lithology

40

Early dikes

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

688

0.010

0.060

0.140

2.34

0.00

2.27

%

ppb Au MDA

688

10.000

37.845

115.286

3.05

0.0

2428

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

1000

Grade

NA

Lithology

50

Post-mineral dikes

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

732

0.121

0.197

0.216

1.09

0.00

1.15

%

ppb Au MDA

732

40.500

75.034

96.222

1.28

0.0

868

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

all X000s

Grade

NA

Lithology

50

Late Dikes

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

780

0.090

0.187

0.210

1.12

0.00

1.15

%

ppb Au MDA

780

31.000

74.523

95.825

1.29

0.0

868

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

2000

Grade

NA

Lithology

NA

Supergene/enriched

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

483

0.960

1.015

0.585

0.58

0.07

3.52

%

ppb Au MDA

483

200.000

223.763

176.462

0.79

9.0

2838

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

3000

Grade

NA

Lithology

NA

Mixed

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

282

0.290

0.336

0.319

0.95

0.00

2.3

%

ppb Au MDA

282

137.000

160.090

109.240

0.68

4.0

825

ppb

 

 

 

 

 

 

 

 

 

Zones

Material

4000

Grade

NA

Lithology

NA

Leached

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

% Cu MDA

620

0.060

0.074

0.066

0.89

0.00

1.21

%

ppb Au MDA

620

190.500

201.923

121.889

0.60

0.0

741

ppb

 

 

 

Zone

30

 

 

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Ag ppm

1,143

1.000

1.520

2.660

1.75

0.000

50.00

ppm

 

 

 

Zone

40

 

 

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Ag ppm

454

0.200

0.320

0.500

1.56

0.000

5.00

ppm

 

 

 

Zone

50

 

 

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Ag ppm

516

0.400

1.030

3.310

3.21

0.000

50.00

ppm

 

 

 

Zone

12340

 

 

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Ag ppm

1,923

0.900

1.000

1.100

1.10

0.000

20.00

ppm

 

 

 

Zone

12342

 

 

 

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Ag ppm

5,175

1.300

1.630

1.620

0.99

0.000

40.10

ppm

 

 

Mirador Norte

 

 

 

 

 

 

 

 

 

primary unmineralized

Cu Zone

1000

 

Capping (Cu)

None

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

141

3.0

3.0

 

 

1.4

4.0

m

Copper

141

0.070

0.075

0.038

0.511

0.010

0.230

%

      Difference

 

 

0%

 

 

 

 

 

Copper Capped

141

0.070

0.075

0.038

0.511

0.010

0.230

%

Gold

141

13

16

16

1.01

1

221

ppb

      Difference

 

 

-5%

 

 

 

 

 

Gold Capped

141

13

15

9

0.62

1

53

ppb

ag_ppm_mda

129

0.1

0.2

0.3

1.36

0.1

2.4

ppm

 

 

 

 

 

 

 

 

 

primary low-grade shell

Cu Zone

1012

 

Capping (Cu)

0.320

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

255

3.0

3.0

 

 

1.8

4.3

m

Copper

255

0.150

0.150

0.064

0.428

0.040

0.510

%

      Difference

 

 

-1%

 

 

 

 

 

Copper Capped

255

0.150

0.147

0.056

0.378

0.040

0.320

%

Gold

252

28

31

30

0.97

2

424

ppb

      Difference

 

 

-5%

 

 

 

 

 

Gold Capped

252

28

29

16

0.55

2

90

ppb

ag_ppm_mda

191

0.1

0.3

0.3

1.16

0.1

2.6

ppm

 

 

 

 

 

 

 

 

 

primary mid-grade shell

Cu Zone

1020

 

Capping (Cu)

0.630

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

1108

3.0

3.0

 

 

1.0

6.0

m

Copper

1108

0.280

0.285

0.097

0.342

0.050

1.560

%

      Difference

 

 

0%

 

 

 

 

 

Copper Capped

1108

0.280

0.283

0.088

0.312

0.050

0.630

%

Gold

1107

51

58

49

0.85

2

1275

ppb

      Difference

 

 

-2%

 

 

 

 

 

Gold Capped

1107

51

57

32

0.55

2

200

ppb

ag_ppm_mda

458

0.6

0.6

0.9

1.47

0.1

18.5

ppm

 

 

 

 

 

 

 

 

 

primary high-grade core

Cu Zone

1040

 

Capping (Cu)

1.200

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

1741

3.0

3.0

 

 

1.0

4.0

m

Copper

1741

0.470

0.497

0.209

0.420

0.070

4.150

%

      Difference

 

 

-1%

 

 

 

 

 

Copper Capped

1741

0.470

0.491

0.162

0.329

0.070

1.200

%

Gold

1741

84

94

61

0.65

4

1423

ppb

      Difference

 

 

-1%

 

 

 

 

 

Gold Capped

1741

84

93

47

0.50

4

400

ppb

ag_ppm_mda

847

1.0

1.1

0.7

0.64

0.1

8.8

ppm

enriched

 

Cu Zone

2000

 

Capping (Cu)

2.100

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

335

2.0

2.1

 

 

1.0

5.0

m

Copper

335

0.650

0.742

0.541

0.730

0.020

3.440

%

      Difference

 

 

-1%

 

 

 

 

 

Copper Capped

335

0.650

0.735

0.518

0.705

0.020

2.100

%

Gold

335

58

74

71

0.97

2

620

ppb

      Difference

 

 

-1%

 

 

 

 

 

Gold Capped

335

58

73

66

0.91

2

400

ppb

ag_ppm_mda

176

0.6

0.9

1.2

1.36

0.1

9.6

ppm

 

 

 

 

 

 

 

 

 

mixed

 

Cu Zone

3000

 

Capping (Cu)

1.700

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

224

2.0

2.5

 

 

1.0

6.0

m

Copper

224

0.215

0.288

0.356

1.239

0.010

3.130

%

      Difference

 

 

-3%

 

 

 

 

 

Copper Capped

224

0.215

0.280

0.311

1.112

0.010

1.700

%

Gold

223

43

57

44

0.77

3

233

ppb

      Difference

 

 

0%

 

 

 

 

 

Gold Capped

223

43

56

44

0.77

3

233

ppb

ag_ppm_mda

150

0.9

1.0

0.9

0.92

0.1

5.8

ppm

 

 

 

 

 

 

 

 

 

leached

 

Cu Zone

4000

 

Capping (Cu)

0.340

 

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

434

5.0

5.0

 

 

2.0

8.0

m

Copper

434

0.040

0.080

0.086

1.084

0.010

0.830

%

      Difference

 

 

-2%

 

 

 

 

 

Copper Capped

434

0.040

0.078

0.078

1.001

0.010

0.340

%

Gold

434

77

103

156

1.51

1

2930

ppb

      Difference

 

 

-6%

 

 

 

 

 

Gold Capped

434

77

97

76

0.78

1

400

ppb

ag_ppm_mda

198

0.5

0.8

1.0

1.28

0.1

6.7

ppm

All Data

 

 

 

 

Capping (Cu/Au)

2.100

400

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

4238

3.0

3.1

 

 

1.0

8.0

m

Copper

4238

0.340

0.344

0.277

0.807

0.010

4.150

%

      Difference

 

 

-1%

 

 

 

 

 

Copper Capped

4238

0.340

0.340

0.257

0.756

0.010

2.100

%

Gold

4233

64

77

84

1.09

1

2930

ppb

      Difference

 

 

-3%

 

 

 

 

 

Gold Capped

4233

64

75

54

0.72

1

400

ppb

ag_ppm_mda

2149

0.7

0.8

0.9

1.06

0.1

18.5

ppm

 

 

 

 

 

 

 

 

 

primary unmineralized

Au Zone

1000

 

Capping (Au)

 

50

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

222

3.0

3.2

 

 

1.0

6.0

m

Copper

222

0.060

0.063

0.046

0.730

0.010

0.320

%

      Difference

 

 

0%

 

 

 

 

 

Copper Capped

222

0.060

0.063

0.046

0.730

0.010

0.320

%

Gold

221

13

16

14

0.86

1

221

ppb

      Difference

 

 

-4%

 

 

 

 

 

Gold Capped

221

13

16

9

0.58

1

50

ppb

ag_ppm_mda

210

0.1

0.4

0.8

2.16

0.1

6.7

ppm

 

 

 

 

 

 

 

 

 

primary low-grade shell

Au Zone

1120

 

Capping (Au)

 

90

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

326

3.0

3.0

 

 

1.0

6.0

m

Copper

326

0.140

0.142

0.082

0.580

0.010

0.740

%

      Difference

 

 

-1%

 

 

 

 

 

Copper Capped

326

0.140

0.140

0.077

0.548

0.010

0.740

%

Gold

323

26

31

28

0.93

2

424

ppb

      Difference

 

 

-4%

 

 

 

 

 

Gold Capped

323

26

29

17

0.58

2

90

ppb

ag_ppm_mda

259

0.1

0.4

0.6

1.53

0.1

5.2

ppm

 

 

 

 

 

 

 

 

 

primary mid-grade shell

Au Zone

1200

 

Capping (Au)

 

200

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

1183

3.0

3.0

 

 

1.0

6.0

m

Copper

1183

0.270

0.269

0.117

0.435

0.010

1.560

%

      Difference

 

 

0%

 

 

 

 

 

Copper Capped

1183

0.270

0.268

0.110

0.412

0.010

0.960

%

Gold

1182

49

56

48

0.86

2

1275

ppb

      Difference

 

 

-2%

 

 

 

 

 

Gold Capped

1182

49

55

31

0.57

2

200

ppb

ag_ppm_mda

497

0.6

0.6

0.9

1.52

0.1

18.5

ppm

 

 

 

 

 

 

 

 

 

primary high-grade core

Au Zone

1400

 

Capping (Au)

 

400

 

Valid N

Median

Mean

Std.Dev.

CV

Minimum

Maximum

Units

Length

2507

3.0

3.1

 

 

1.0

8.0

m

Copper

2507

0.440

0.428

0.315

0.736

0.010

4.150

%

      Difference

 

 

-1%

 

 

 

 

 

Copper Capped

2507

0.440

0.423

0.288

0.680

0.010

2.100

%

Gold

2507

83

99

97

0.98

1

2930

ppb

      Difference

 

 

-3%

 

 

 

 

 

Gold Capped

2507

83

96

57

0.59

1

400

ppb

ag_ppm_mda

1183

1.0

1.1

0.8

0.75

0.1

9.6

ppm

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

  CORRIENTE RESOURCES INC.  
  (Registrant)  
   
Date: December 18, 2006  

By:   

/S/ DARRYL F. JONES  
  Name: Darryl F. Jones
  Title: Chief Financial Officer