Technical Report for the Guadalupe de Los Reyes - Vista Gold Guadalupe de los Reyes... · Technical Report for the Guadalupe de Los Reyes Gold-Silver Project, State of Sinaloa, Western

Technical Report for the Guadalupe de Los Reyes Gold-Silver Project, State of Sinaloa, Western Mxico Prepared for Vista Gold Corporation July 17, 2003 9203.04

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Technical Report for the Guadalupe de Los Reyes Gold-Silver Project, State of Sinaloa, Western Mexico Prepared for Vista Gold Corporation July 17, 2003 9203.04 Prepared by Pincock, Allen & Holt Ral Borrastero Leonel Lpez, C.P.G. Mark G. Stevens, C.P.G.

A Division of Hart Crowser 274 Union Boulevard, Suite 200 Lakewood, Colorado 80228-1835 Fax 303.987.8907 Tel 303.986.6950

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CONTENTS Page

1.0 EXECUTIVE SUMMARY 1.1

1.1 Location 1.1 1.2 Ownership 1.1 1.3 Geology and Mineralization 1.2 1.4 Exploration and Project Data 1.3 1.5 Geologic Resources 1.4 1.6 Conclusions and Recommendations 1.5

2.0 INTRODUCTION AND TERMS OF REFERENCE 2.1

2.1 Terms of Reference 2.1 2.2 Purpose of the Technical Report 2.1 2.2.1 Sources of Information 2.1 2.3 Site Visit 2.2 2.4 Terms and Definitions 2.2 2.5 Units 2.2

3.0 DISCLAIMER 3.1

4.0 PROPERTY DESCRIPTION AND LOCATION 4.1

4.1 Property Description 4.1 4.2 Location 4.1 4.3 Project Ownership 4.1 4.4 Guadalupe de Los Reyes Concessions Option Agreement 4.3 4.5 Mineral Tenure 4.5 4.6 Surface Land Ownership 4.5 4.7 Environmental and Permitting 4.8

5.0 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE

AND PHYSIOGRAPHY 5.1 5.1 Accessibility 5.1 5.2 Climate and Physiography 5.1 5.3 Local Resources and Infrastructure 5.1

6.0 HISTORY 6.1

7.0 GEOLOGICAL SETTING 7.1 Pincock, Allen & Holt Page i 9203.04 July 17, 2003

CONTENTS (Continued) Page

7.1 Guadalupe de Los Reyes Project Regional Geologic Setting 7.1 7.2 El Zapote Deposit Geology 7.3 7.3 Guadalupe Mine Deposit 7.5 7.4 Chiripa San Miguel Noche Buena Deposits 7.5 7.5 Tahonitas Deposit 7.10

8.0 DEPOSIT TYPES 8.1

9.0 MINERALIZATION 9.1

10.0 PROJECT EXPLORATION 10.1

11.0 PROJECT DRILLING 11.1

12.0 SAMPLING METHODOLOGY 12.1

13.0 SAMPLE PREPARATION, ANALYSIS AND SECURITY 13.1

14.0 DATA VERIFICATION 14.1

15.0 ADJACENT PROPERTIES 15.1

16.0 METALLURGICAL TESTING 16.1

16.1 Historical Metallurgical Test Work 16.1 16.2 Recent Metallurgical Test Work 16.2

17.0 MINERAL RESOURCE ESTIMATES 17.1

17.1 Introduction 17.1 17.2 Computerized Modeling 17.1 17.3 Rock Models 17.4 17.4 Grade Models 17.4 17.5 Geologic Resources 17.6 17.5.1 Vista Classified Resources 17.8 17.6 Geologic Reserves 17.8 17.7 Additional Resource Potential 17.8

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18.0 OTHER RELEVANT DATA AND INFORMATION 18.1

19.0 INTERPRETATION AND CONCLUSIONS 19.1

20.0 RECOMMENDATIONS 20.1

21.0 REFERENCES 21.1

22.0 ADDITIONAL REQUIREMENTS FOR TECHNICAL REPORTS ON DEVELOPMENT PROPERTIES AND PRODUCTION PROPERTIES 22.1

23.0 ILLUSTRATIONS 23.1

24.0 CERTIFICATE OF QUALIFICATION 24.1

TABLES

1-1 Vista Mineral Resources (Within Optioned Claims) 1.4 4-1 Vista Gold Mineral Concessions Currently Under Option 4.3 4-2 Mineral Concessions of The Guadalupe de Los Reyes District 4.6 6-1 Summary of Projection Guadalupe de Los Reyes Mining District 6.1 9-1 General Deposit Data 9.2 11-1 Data Verification, Meridian Gold Drill Hole Location 11.5 11-2 Guadalupe de Los Reyes Project Drilling and Drill Samples Assayed. 11.9 12-1 RC Hole Cutting Samples and Geochemical Sampling 12.1 12-2 RC Hole Cutting Samples for Metallurgical Testworks 12.2 16-1 Mineralized Material Sample Identification Head Assays. 16.2 16-2 Results of Cyanide Bottle Roll Tests 16.3 16-3 Results of Column Leach Tests 16.4 17-1 Guadalupe de Los Reyes Project Composite Statistics 17.3 17-2 Mineral Deposits Search Interpolation Parameters Based on Variography(*) 17.5 17-3 Block Model Statistics of El Zapote and Guadalupe Laija Deposits (*) 17.5 17-4 Comparison of SRK & Minorex Krige and PAH NN Block Models 17.6

Pincock, Allen & Holt Page iii 9203.04 July 17, 2003


17-5 Vista Mineral Resources (Within Gaitn Concessions) @ 0.5 g/t Au 17.7 17-6 Vista Mineral Resources (Within Gaitn Concessions) @ 1.0 g/t Au 17.7

FIGURES

4-1 General Location Map 4.2 4-2 Guadalupe de Los Reyes Mining District Concessions Map 4.7 7-1 Guadalupe de Los Reyes Mining District Geological Setting 7.2 7-2 El Zapote Deposit, Cross Section 5450 (Looking Northwest) 7.4 7-3 Guadalupe Mine Underground Development 7.6 7-4 Guadalupe Deposit Cross Section 4900 (Looking West) 7.7 7-5 San Miguel Deposit Cross Section 5150 (Looking Northwest) 7.8 7-6 Noche Buena Deposit Cross Section 4600 (Looking Northwest) 7.9 7-7 Tahonitas Deposit Cross Section 4650 (Looking Northwest) 7.11 8-1 Illustration Of Epithermal Model 8.2 9-1 Deposits Covered by Vista Optioned Claims 9.3 11-1 Correlation Collar/Topography For The El Zapote Deposit 11.2 11-2 Correlation Collar/Topography For The Chiripa San Miguel Deposit 11.3 11-3 Correlation Collar/Topography For The Guadalupe Laija Deposit 11.4 11-4 El Zapote Tahonitas Chiripa Drill Hole Locations 11.6 11-5 San Miguel Noche Buena Drill Hole Locations 11.7 11-6 Guadalupe Mine Drill Hole Locations 11.9 13-1 Guadalupe de Los Reyes Check Assay Results 13.3 15-1 Deposits Covered by Vista Optioned Claims 15.2 17-1 Indicated Resources Tonnage Grade variability at different Cutoffs for the El Zapote deposit 17.9 17-2 Indicated Resources Tonnage Grade variability at different Cutoffs for the Tahonitas deposit 17.10 17-3 Indicated Resources Tonnage Grade variability at different Cutoffs for the Noche Buena deposit 17.11 17-4 Indicated Resources Tonnage Grade variability at different Cutoffs for the San Miguel - Chiripa deposit 17.12 17-5 Indicated Resources Tonnage Grade variability at different Cutoffs for the Guadalupe - Laija deposit 17.13

Pincock, Allen & Holt Page iv 9203.04 July 17, 2003

1.0 EXECUTIVE SUMMARY

Pincock, Allen & Holt Ltd. (PAH), a division of Hart Crowser Inc., was retained by Vista Gold Corp. (Vista), to prepare a Technical Report in accordance with Canadian National Instrument 43-101, with regards to the Guadalupe de Los Reyes Gold-Silver Project. The Guadalupe de Los Reyes mineral resource estimates for the El Zapote and other deposits within the Projects area were based on reverse circulation drilling programs carried out by Northern Crown Mines (NCM) from 1994 to 1997. Additional drilling on various of the deposits was performed by Meridian Gold Corporation in 2002. This Technical Report incorporates the information to reflect the most recent Projects resource estimates.

1.1 Location

The Guadalupe de Los Reyes Gold-Silver Project is located in the State of Sinaloa, in western Mxico, at approximately half of the distance between the cities of Mazatln and Culiacn. The Project area is accessed by a 30-kilometer dirt road from Cosal, a city of approximately 17,000 inhabitants. The city of Cosal is connected to the cities of Mazatln and Culiacn by a 55-kilometer paved highway plus 100 kilometers of super highway, or by small aircraft from a local airstrip to international airports of Durango, Mazatln and Culiacn.

1.2 Ownership

Vista has agreed with Mr. Enrique Gaitn on terms and conditions to acquire the property rights as set for in an Option to Purchase Proposal dated on January 3, 2003 upon approval by the Board of Directors, and the Canadian Stock Exchange. The Option Agreement terms and conditions include the purchase of 100 percent of the interest held by Mr. Gaitn in the Guadalupe de Los Reyes project area, including mineral rights in three exploration and two exploitation concessions with a total area of 596.9780 hectares (1,475.1326 acres). The Option terms and conditions are indicated in a copy of the document supplied by Vista, as follows:

1. A 4-month period for due diligence includes monthly payments to Mr. Gaitn of $20,000.00. Vista may terminate the option at any time.

2. At 4 months or before, Vista and Gaitn may sign an Option to Purchase Agreement upon a payment of $400,000.00 less any advanced amounts, plus Vista will pay 2002 and half of 2003 concession holding costs of up to $15,000.00.

3. At the first anniversary of the Option to Purchase Agreement Vista would pay to Gaitn $500,000.00 or the equivalent in Vista shares.

4. At the second and subsequent anniversaries Vista would pay to Gaitn a yearly amount of $100,000.00 up to a total amount of $500,000.00.

Pincock, Allen & Holt 1.1 9203.04 July 17, 2003

5. Vista will pay to Gaitn a 2.00 percent net smelter return (NSR) on all gold and silver production from the property. This royalty may be purchased by Vista at any time for $1,000,000.00.

PAH notes that the transaction involves the purchase of five concessions that cover the mineral rights of part of the deposits zones within the Guadalupe de Los Reyes mining district. Therefore the Vista optioned concessions only cover part of the mineral deposits that were identified and drilled by NCM and other companies. Vista has initiated negotiations to acquire adjacent mineral concessions to consolidate ownership of the mining district.

Small-scale mining activity in the Guadalupe de Los Reyes district was carried out for over 150 years until the 1950s. Originally high-grade silver and gold ore was extracted by underground methods from a vein system and shipped by horseback to Mazatln. Most of the production was shipped from Mazatln to Germany. High-grade gold ore was processed by amalgamation, flotation, and in brick-concrete vats by cyanidation.

The Guadalupe de Los Reyes project was previously under option by Northern Crown Mines Ltd., and explored by a program that included regional and local geological studies, drilling by reverse circulation (375 drill holes, 36,106 m), geologic modeling of the El Zapote deposit for resource estimates, along with preliminary metallurgical test work and economic analysis of El Zapote. Results of these studies of El Zapote were analyzed and compiled in a Pincock, Allen & Holt Prefeasibility (PAH) Report dated January 28, 1998, produced by a combination of efforts from various specialized contracting firms under PAH lead. Assistance for the Prefeasibility Study was provided by Gochnour & Associates in environmental studies; Steffen, Robertson & Kirsten in computer modeling and resource estimates; Tecnoco International Corporation in metallurgical studies; and by WESTEC in geotechnical studies, design and costs estimates. Though not part of the Prefeasibility, other deposits within the project area were also drilled and modeled for preliminary resource estimates, including the Guadalupe mine (Laija and West zones), Chiripa-San Miguel- Noche Buena, Tahonitas, Mariposa, and El Orito zones.

In December 2000, the Guadalupe de Los Reyes project was optioned from NCM by Meridian Gold Company (Meridian). Meridian carried out a confirmatory drilling campaign to test some previously indicated high-grade mineralized areas. Drilling included 23 drill holes (2,732 m) between May 16 to June 19, 2001. Meridians drilling results did not meet the Companys objectives of grade and continuity in the areas tested and the mineral rights were returned to NCM. Subsequently, in late 2002, NCM cancelled the contracts to acquire the property and returned the rights to the original concessionaires.

1.3 Geology and Mineralization

The Guadalupe de Los Reyes project occurs in the western side of the Sierra Madre Occidental Province, a late Cretaceous to Tertiary age volcanic sequence that extends for hundreds of kilometers from the Neo-Volcanic Belt in Central Mxico to the Basin and Range Province in the


north part of the country. This geologic province encloses a great number of major gold and silver deposits of historic production within Mining Districts of world importance, such as Hostotipaquillo, Bolaos, Guanajuato, La Cinega, Tayoltita, Guadalupe de Los Reyes, Topia, Batopilas, Dolores, etc. Mineralization in the project area has been found along a series of northwesterly trending structural zones in andesites of Tertiary age of the Lower Volcanic Sequence.

In the Guadalupe de Los Reyes deposits, mineralization typical of low sulfidation epithermal systems occurs in westward dipping structural zones that range from a few meters to several tens of meters in thickness. The gold occurs as microscopic-sized, free to quartz-encapsulated particles. associated with silver. Pyrite content within the deposit is generally less than 1.0 percent and only occasionally up to 3.0 percent in individual samples. Since the gold does not occur in pyrite, oxidation of the pyrite does not appear to be a major factor in metallurgical gold liberation and recovery. The silver to gold ratio in the deposit is approximately 15:1, based on total silver to total gold (fire assay).

The Guadalupe de Los Reyes project includes eight target areas that have been identified along three major structural zones. Some of these targets have bulk tonnage potential, which may be amenable to open-pit mining, such as El Zapote, San Miguel, Guadalupe Mine (Laija and West), Tahonitas, and Noche Buena zones. The El Zapote zone has received the most extensive exploration to date.

1.4 Exploration and Project Data

Exploration of the Guadalupe de Los Reyes project by NCM has included the reverse circulation drilling of 375 holes, for a total of 36,106 meters; including 197 holes with 15,728 meters in the El Zapote deposit. Drill hole locations at El Zapote are irregularly placed on lines that are spaced at approximately 25 meters, with hole spacing along the lines averaging approximately 30 meters. PAH finds that the drill hole spacing is adequate for establishing a reasonable degree of confidence necessary for defining resources at a prefeasibility level.

Drilling of the other deposits within the projects area has been developed on lines that are spaced between 50 to 100 meters. The Guadalupe mine (Laija and West) included 78 drill holes with a total of 10,547 meters; the San Miguel deposit was drilled with 33 holes (3,674 meters); the Noche Buena deposit was explored with 25 drill holes (2,593 meters); the Tahonitas deposit included 33 holes with a total of 2,258 meters drilled; El Orito deposit included 8 drill holes with a total of 1,140 meters; and the Mariposa deposit was drilled with 1 hole of 166 meters. Meridian drilled 23 reverse circulation holes with a total of 2,732 meters in several of the deposits.

NCM=s reverse circulation hole sampling program consisted of collecting samples at 1.52-meter intervals (5 feet) from 133 mm (5.25-inch) diameter holes. Bondar-Clegg laboratories in Vancouver, British Columbia, Canada analyzed most of the project drill hole samples. NCM had approximately 10 percent of the sample intervals in the mineralized zone sent for duplicate analysis by Min-En Laboratories to evaluate the quality of the sample analysis. Overall, PAH found that the analytical checks results were within standard industry practice.


The analytical results from the drilling were compiled by NCM in a computer database that was used as the basis for the subsequent El Zapote resource modeling by Steffen, Robertson & Kirsten (SRK) and Minorex, and resource reporting by PAH. The computer block model for the El Zapote deposit was developed by SRK using a block size of 5-by-5 meters in plan with a 5-meter bench height. A block model representation of the mineralized zone envelope was created from geologic cross sections. In addition, the model flagged areas of previous underground workings. Block models of gold and silver grades were then created by SRK for the El Zapote deposit using ordinary kriging estimation methods. Individual blocks were assigned grade from capped composites grades within the mineralized envelope.

Minorex developed geologic block models for the other deposits within the project area following similar parameters as those determined by SRK for the El Zapote deposit. PAH recovered the Guadalupe Laija deposit models and evaluated the other models on a global and local basis and found that models tended to have smoothed grade distributions, as is typical with the kriging approach. Based on review of the models in digital and hard copy forms, PAH believes that the mineralized zones are adequately represented by the models.

1.5 Geologic Resources

The resulting geologic resource for the Guadalupe de Los Reyes deposits includes all material in the models, within Vistas optioned concessions boundaries, without regard to mineability. At a 0.5 g/t Au cutoff the indicated resource consists of 6.3 million tonnes of indicated resources at an average grade of 1.36 g/t Au and 23.0 g/t Ag. In addition 3.8 million tonnes of inferred resources exist at 2.0 g/t Au and 66 g/t Ag, as shown in Table 1-1. The resource is based on a density of 2.6 tonnes per cubic meter. Previously mined stope tonnages of 166,000 tonnes from the El Zapote deposit, and 668,000 tonnes from the Guadalupe Laija deposit have been subtracted from the resource total. Blocks within 30 meters of a composite value were classified as an indicated confidence category, while blocks between 30 to 60 meters were classified as inferred.

TABLE 1-1 Vista Gold Corporation. Guadalupe de Los Reyes Project Vista Mineral Resources (Within Optioned Claims) @ 0.5 g/t Au. Deposit INDICATED

K Tonnes Gold G/t

Silver G/t

INFERRED K Tonnes

Gold g/t

Silver g/t

El Zapote (*) 4,209 1.34 9.3 107 1.78 8.5 Tahonitas 404 1.41 48.4 290 1.54 52.0 Noche Buena 459 1.18 23.6 1,144 1.13 24.9 San Miguel Chiripa 515 1.15 70.8 173 1.80 60.3 Guadalupe Laija (*) 751 1.71 53.2 2,106 2.59 93.4 Guadalupe West 9 0.59 19.1 20 0.66 15.5 TOTAL 6,347 1.36 23.0 3,840 2.01 65.6 TOTAL CONTAINED Gold Ounces

(rounded) 277,600 4,697,800 247,850 8,099,300

(*) Resource has been adjusted to reflect material removal from old u/g workings.


1.6 Conclusions and Recommendations

Because there has been no feasibility study completed evaluating the economic viability of the resources documented in this report, none of the resources can be advanced to mineral reserves at this time.

Additional resources may be confirmed with complementary drilling in the near surface areas where updip extensions of the mineralized zones at the El Zapote are insufficiently drilled, as well as in the San Miguel, Guadalupe Mine, Tahonitas, and Noche Buena deposits to improve the potential for the Projects economic development.

PAH believes that the exploration and sampling programs on the Guadalupe de Los Reyes project deposits have been carried out using industry standard practices and methodologies and that the resulting data are representative of the mineralization in the deposits. PAH confirms that the resource modeling based on these data was also conducted using standard industry engineering practices and believes that the results represent the deposits tonnes and grades within acceptable accuracy limits.

NCM initiated studies to gather data for the necessary environmental baseline requirements to satisfy permitting in the summer of 1997; no fatal flaws have been discovered that would prohibit construction, operation, or closure of the project according to studies made by Gochnour & Associates. Acid Base Accounting of representative mineralized material and waste samples did not reveal any indication that the material would generate acid.

PAH is of the opinion that the property is of sufficient merit to justify additional exploration programs and investments.


2.0 INTRODUCTION AND TERMS OF REFERENCE

2.1 Terms of Reference

Pincock, Allen & Holt (PAH) was retained by Vista Gold Corporation (Vista), to prepare a Technical Report in accordance with Canadian National Instrument 43-101 for the Guadalupe de Los Reyes Gold-Silver Project. PAH reviewed Northern Crown data as well as additional drill holes developed by Meridian Gold Corporation in four areas of the Guadalupe Los Reyes Project .

Personnel assigned for this study includes the following:

Mark G. Stevens, C.P.G., Principal Geologists and Project Manager Ral Borrastero, Senior Geologist Leonel Lpez, C.P.G., Principal Geologist Other PAH personnel as required

2.2 Purpose of the Technical Report

Vista has agreed with Mr. Enrique Gaitn Enrquez on terms and conditions to acquire the Guadalupe de Los Reyes property rights as set forth in a Purchase Proposal dated January 3, 2003 upon approval by Vista Board of Directors, and the Toronto Stock Exchange. Mr. Gaitns property rights include concessions that cover approximately 7 percent (596.978 hectares) of the mining district, but cover most of the area of the main exploration targets within the Guadalupe de Los Reyes project area including the El Zapote, Guadalupe Mine, San Miguel, Noche Buena, and Tahonitas deposits. PAH has not reviewed the legal status of the mineral concessions. This Technical Report was completed to meet the requirements of National Instrument 43-101.

2.2.1 Sources of Information

Technical data on the Guadalupe de Los Reyes Project was supplied by Vista to PAH, including field recorded information, maps, logs and reports generated by personnel under contract with NCM and its Mexican subsidiaries Minera Tatemas, S.A. de C.V. and Minera Sierra Pacfico, S.A. de C.V., and reports prepared by specialized contractors. A list of reports and files is presented in Section 21.0, References. This information included data on the last exploration program developed by Meridian Gold Company during 2002 in various zones of the Guadalupe de Los Reyes Project.

In addition to the above indicated sources of information, PAHs own references included a Prefeasibility Report (January 28, 1998) carried out by a combination of efforts from various specialized contracting firms under PAH lead, with emphasis on the El Zapote deposit. The Prefeasibility Report was prepared by PAH with assistance from Gochnour & Associates in environmental studies; by Steffen, Robertson & Kirsten in computer modeling and resource


estimates; by Tecnoco International Corporation in metallurgical studies; and by WESTEC in geotechnical studies, design and costs estimates.

Previous studies by PAH in the Guadalupe de Los Reyes mining district, as contracted by Pan Atlantic Group Co., Inc. included geologic mapping and direct exploration investigations by underground development and evaluation of the Mariposa Project as reported in June 20, 1992.

2.3 Site Visit

Project representatives for the Prefeasibility study visited the site from July 27 to July 30, 1997. The site visit team included NCM representatives Bob Barnes and Ramon Faras. Technical team representatives included Mark Stevens (PAH), Gary Cantrell (PAH), Allan Breitenbach (WESTEC), Ted Izzo (Tecnoco), and Pat Gochnour (Gochnour & Associates), all acting as Independent Engineers.

Preparation of this Technical Report by PAH included a site visit to review the projects current status, present infrastructure conditions and the exploration efforts carried out by NCM and Meridian. The site visit was performed by PAHs representative Leonel Lpez from May 20 to May 22, 2003, as a Qualified Person (QP), and Mr. Gary Parkison, consulting geologist on behalf of Vista.

2.4 Terms and Definitions

Vista refers to Vista Gold Corporation, Gaitn refers to Mr. Enrique Gaitn Enrquez, PAH refers to Pincock, Allen and Holt, Inc., NCM refers to Northern Crown Mines, Meridian refers to Meridian Gold Corporation, Luismin refers to Desarrollos Mineros del Pacfico, S.A. de C.V. or Minas de San Luis, S.A. de C.V. (currently owned by Wheaton River Minerals); Guadalupe or Guadalupe de Los Reyes refers to the Guadalupe de los Reyes Project, Prefeasibility refers to the study by PAH dated January 28, 1998, Gochnour refers to Gochnour and Associates, SRK refers to Steffen, Robertson & Kirsten, Tecnoco refers to Tecnoco International Corporation, WESTEC refers to WESTEC geotechnical engineering associated, Minorex refers to Minorex Consulting Ltd., RC refers to reverse circulation drilling, g/t Au refers to grams per metric tonne, tpd refers to metric tonnes per day, mm refers to millimeters, and $ refers to US currency.

2.5 Units

Units in this report are metric unless otherwise noted. Tonnage figures are dry, metric tonnes, unless otherwise stated. Precious metal content is reported in grams per metric tonne (g/t) or grams (g), except where otherwise stated. All coordinates used for location and elevations referenced on maps and text in this report are based on newly obtained Universal Transverse Mercator and have been referred to by project personnel as the Global UTM system, and they are based on the Map Datum NAD27-Mxico.


3.0 DISCLAIMER

This report was prepared for Vista Gold Corporation by the independent consulting firm of Pincock, Allen & Holt, and is based in part on information not within the control of either Vista or PAH. While it is believed that the information contained herein will be reliable under the conditions and subject to the limitations set forth herein, neither Company nor consultants guarantee the accuracy thereof. The use of this report or any information contained therein shall be at the users sole risk, regardless of any fault or negligence of Company or the consultants.

PAH has, in part, relied upon portions of the reports of other persons who are believed to be Qualified Persons as defined as Canadian NI 43-101 (see References).


4.0 PROPERTY DESCRIPTION AND LOCATION

4.1 Property Description

The Guadalupe de Los Reyes Project includes eight target areas that have been identified by NCM and previous operators along four major structural zones within a total area of over 8,630 hectares (21,330 acres). Several of these targets have bulk tonnage potential which may be amenable to open-pit mining, including the El Zapote, San Miguel, La Chiripa, Guadalupe Mine (Laija, West), Tahonitas, and Noche Buena. The El Zapote zone has received the most extensive modern exploration to date. Five of these zones are partly covered by Mr. Gaitns mineral concessions currently optioned to Vista Gold. The Guadalupe Mine, El Zapote, San Miguel, and Mariposa deposits have previously been mined by underground methods.

This Technical Report presents a review of the mineral resources under Vista Golds control, that are controlled by the mineral rights held by Mr. Gaitns concessions within the Guadalupe de Los Reyes Project, including portions of the El Zapote, San Miguel, Guadalupe (Laija and West), Tahonitas, and Noche Buena. Recommendations are made for additional land acquisitions and exploration studies to complement development of the projects mineralized zones.

4.2 Location

The Guadalupe de Los Reyes Project is located within the Guadalupe de Los Reyes Mining District in the western foothills of the Sierra Madre Occidental mountain range, approximately 110 kilometers by air (200 kilometers by road) north of the coastal city of Mazatln. The El Zapote and other deposits occur in the south-central part of the district, approximately 20 kilometers by air (30 kilometers by road) southeast of the town of Cosal (17,269 inhabitants, INEGI 2000), in Sinaloa State. General geographic coordinates for the Guadalupe Los Reyes mining district are approximately: N-24 16 42" and W-106 30 15" (13R 0347019-E, 2685586-N, 711m at the village of Guadalupe Los Reyes). Figure 4-1 shows a general location map.

4.3 Project Ownership

The mineral concessions contracted by Vista include two titled concessions for exploitation, and three titled concessions for exploration, covering a total surface of 597.0 hectares (1,475.1 acres), that are all located in the Municipality of Cosal within the State of Sinaloa, Mxico. These are presented in Table 4-1 and Figure 4-2.


TABLE 4-1 Vista Gold Corporation Guadalupe de Los Reyes Project Vista Gold Mineral Concessions Optioned from Gaitn

Exploration Claims Name Area (ha) Title Number La Victoria 199.2896 192499 Prolongacin del Recuerdo (1) 91.5951 194053 Prolongacin del Recuerdo Dos 25.8927 192500 316.7774 Exploitation Claims Name Area (ha) Title Number Arcelia Isabel (2) 60.3723 193499 Dolores 219.8283 180909 280.2006 Total Hectares 596.9780 (1,475.1326 acres)

(1) Includes 2 fractions of the claim. PAH has no references to confirm this inclusion. (2) Includes 1 fraction of the claim. PAH has no references to confirm this inclusion.

Exploration concessions are granted for renewable 6-year terms and the exploitation concessions for renewable 50-year terms. The title records are maintained in Culiacn, the state capital city of Sinaloa, at the Mining Agency (Agencia de Minera), at the Delegacin Regional de Minera in Durango city, and the Central Mining Registry in Mxico City (Direccin General de Minas). PAH has not reviewed the property legal status and only includes the following terms of the option agreement for general reference.

4.4 Guadalupe de Los Reyes Concessions Option Agreement

By agreement dated January 3, 2003, with Mr. Enrique Gaitn Enrquez, owner of all mineral rights included in the mining claims listed, Vista holds an exclusive option to earn a 100 percent interest in three exploration and two exploitation concessions comprising part of the Guadalupe de Los Reyes Project for a total consideration of $1,400,000 plus a 2.0 percent NSR royalty valued at $1,000,000.00, which may be purchased by Vista at any time.

The option terms and conditions are indicated in copy of document supplied to PAH by Vista as follows:

1. A 4-month period was granted to Vista for due diligence studies. This includes monthly payments to Mr. Gaitn of $20,000.00, which would be deducted from the first purchase payment.

2. At the end of the 4-month period, or before, Vista may sign with Mr. Gaitn an Option to Purchase Agreement upon a first purchase payment of $400,000.00. Vista will reimburse to Mr. Gaitn up to $15,000.00 due to concession holding costs for 2002 and half of 2003.


3. At the first anniversary from the signature date of the Option to Purchase Agreement Vista would pay to Mr. Gaitn the amount of $500,000.00 or the equivalent in Vista shares.

4. At the second and subsequent anniversaries from the signature date of the Option to Purchase Agreement Vista would pay to Mr. Gaitn the amount of $100,000.00 up to $500,000.00.

5. Vista would pay to Mr. Gaitn a 2.00 percent net smelter return (NSR) royalty on all gold and silver produced from the property. This royalty may be purchased by Vista at any time for the amount of $1,000,000.00.

Vista supplied PAH with electronic information of the Guadalupe de Los Reyes mining district concessions map and ownership as presented by a mining registered surveyor (Perito Minero), Mr. Vctor Juvera who was contracted by Vista to investigate the current legal status of land registration. Please refer to Figure 4-2. In accordance with PAHs understanding of the property legal status antecedents, it is recommended for Vista to take in consideration or clarify the following observations in order to secure ownership of the Projects rights:

(1) The concession 10 de Mayo was cancelled by the Mining Department due to failure on applying for exploitation rights after the exploration rights ended. The claim is now owned by Mr. Jaime Guinea Gonzlez y Socios (Dr. Matthew D. Grays report) while in the concessions map it appears as owned by Minera Tatema (Mr. Enrique Gaitn Enrquez).

(2) The Arcelia Isabel concession presents a fraction that may be titled apart from the main portion of the claim. Clarification information should be obtained by the Perito Minero.

(3) The Prolongacin del Recuerdo concesin presents two fractions of the claim, which may be titled independently from the main portion of the claim. Clarification information should be obtained by the Perito Minero.

(4) The claims under Minera Sierra Pacfico, S.A. de C.V., a wholly owned subsidiary of Northern Crown Mines appear as valid concessions although NCM has released the project. It may be more convenient for Vista to negotiate the acquisition of the claims directly from NCM instead of allowing for the rights to be released by the Mines Department, when any person may apply for the mineral rights.

(5) Desarrollos Mineros del Pacfico, S.A. de C.V. is a wholly owned subsidiary of Luismin, which in turn is now owned by Wheaton River Minerals.

(6) A group of Associates from the city of Culiacn apparently owns numerous concessions. These were contracted under a purchase agreement by Compaa Minera Mariposa, which sub-contracted them to NCM. It appears that these claims have been returned to the


original concessionaires; if that is the case, then negotiations with these residents of the city of Culiacn maybe undertaken, or take over the purchase agreement.

(7) Compaa Minera Mariposa may be ready to drop the Martha 1 concession or willing to negotiate under favorable terms.

To consolidate the ownership of concessions that cover the mineral rights for all the area of the Guadalupe de Los Reyes Mining District, Vista must negotiate and acquire other claims as is shown in Table 4-2. Figure 4-2 shows the location and configuration of all the mineral concessions in the Guadalupe de Los Reyes District as reported by the Perito Minero; however, Vista has noted some current changes in ownership for which PAH has not seen documentation.

4.5 Mineral Tenure

All mining and environmental activities in Mxico are regulated by the Direccin General de Minas and by the Secretara del Medio Ambiente from Mxico city, under the corresponding Laws and Regulations. All minerals below-surface rights lie with the State; while surface rights are owned by ejidos (communities) or individuals, allowing them the right of access and use of their land.

Provisions are included in the Mining Law to permit expropriation of surface rights for development of projects that are of general economic interest, including mining operations.

4.6 Surface Land Ownership

The surface rights to the Guadalupe de Los Reyes Project are held by the Ejido Tasajera, which owns most of the Projects land and recognizes individual rights to its members farming, living or using the land for their benefit. NCM and other operators in the area have negotiated surface rights agreements with those individual holders and the Ejido Tasajera governing board. An important consideration is the traditional use of land, which in fact, recognizes that mining is the preferred use of the land in and around old mining workings.

According to Mr. Gaitn and by PAHs experience within the region, there is a good working relationship with people of the Ejido Tasajera, since many of the inhabitants are necessarily contracted when work is carried out in the exploration or mining operations. No labor or access problems have been reported by NCM, Meridian or other mining operators within the area.

To operate within the Laws and Regulations of Mxico, Vista must negotiate the land rights before initiating development of any considerable mining operations in the Project area. It should be established if any agreements between previous operators, NCM and Mr. Gaitn, and the Ejido Tasajera are still valid.


TABLE 4-2 Vista Gold Corporation Guadalupe de Los Reyes Project Concessions Of The Guadalupe Los Reyes District

Concession Name TITTLE CONCESSIONAIRE NOTES La Victoria 210803 Minera Tatemas, S.A. de C.V. Mr. Enrique Gaitn E. (1)

Prolong. Del Recuerdo 210497 Minera Tatemas, S.A. de C.V. Mr. Enrique Gaitn E. (1)

Prolong. Del Recuerdo 2 209397 Minera Tatemas, S.A. de C.V. Mr. Enrique Gaitn E. (1)

Arcelia Isabel 193499 Mr. Enrique Gaitn E. Mr. Enrique Gaitn E. (1)

Dolores 180909 Jaime Guinea G. Y Socios Mr. Enrique Gaitn E. (1)

10 de Mayo 208790 Minera Tatemas, S.A. de C.V. Jaime Guinea G. y Soc.(*)

Seis de Enero Exp-9857 Jaime Guinea G. Y Socios Jaime Guinea G. y Socios.

El Faisn 211471 Minera Sierra Pacfico, S.A. de C.V. Northern Crown Mines (?)

Patricia 212775 Minera Sierra Pacfico, S.A. de C.V. Northern Crown Mines (?)

San Manuel 188187 Minera Sierra Pacfico, S.A. de C.V. Northern Crown Mines (?)

Santo Nio 211513 Minera Sierra Pacfico, S.A. de C.V. Northern Crown Mines (?)

Tominil 205768 Minera Sierra Pacfico, S.A. de C.V. Northern Crown Mines (?)

Tominil Fraccin 205769 Minera Sierra Pacfico, S.A. de C.V. Northern Crown Mines (?)

Guadalupe Norte I 210471 Desarrollos Mineros del Pacfico, SACV Luismin (Wheaton River)

Los Reyes Dos 214131 Desarrollos Mineros del Pacfico, SACV Luismin (Wheaton River)

Los Reyes Tres 214303 Desarrollos Mineros del Pacfico, SACV Luismin (Wheaton River)

Los Reyes Cuatro 217757 Desarrollos Mineros del Pacfico, SACV Luismin (Wheaton River)

Los Reyes Cinco 216632 Desarrollos Mineros del Pacfico, SACV Luismin (Wheaton River)

Los Reyes Fracc. Norte 212757 Desarrollos Mineros del Pacfico, SACV Luismin (Wheaton River)

Los Reyes Fracc. Sur 212758 Desarrollos Mineros del Pacfico, SACV Luismin (Wheaton River)

Los Reyes Fracc. Oeste 210703 Desarrollos Mineros del Pacfico, SACV Luismin (Wheaton River)

Martha I 200768 Ca.Minera Mariposa,S.A. de C.V. Pan Atlantic Group

Nueva Esperanza 184912 Jos Zazueta Gaxiola. Socios Culiacn.

San Miguel 185761 Jos Zazueta Gaxiola. Socios Culiacn.

El Padre Santo 196148 Cruz Lpez Arredondo y Socios. Socios Culiacn.

Norma 177858 Cruz Lpez Arredondo y Socios. Socios Culiacn.

San Pablo 212752 Vigente Socios Culiacn (*).

San Pedro 212753 Vigente Socios Culiacn (*).

(1) Vista Gold Corp. Option. (?) Dropped or still held by NCM. (*) It is of PAH understanding. Research by: Mr.Vctor Juvera (Perito Minero).


4.7 Environmental and Permitting

According to Mr. Gaitn there are no existing environmental liabilities recognized on the property. Previous mining workings are limited in extent and waste dumps are relatively small. The Guadalupe underground operation was developed along narrow veins extracting highly selected ores and only small waste dumps were formed during the long history of production. Near the village of Guadalupe Los Reyes the remains of the cyanidation vats that were in operation until the 1950s have been reclaimed by vegetation, and if any contamination existed, it has been washed away by the mines drainage. This is located in a canyon independent and apart from the El Zapote deposit. No acid drainage from the old Guadalupe mine has been reported. Currently the water that drains out from the old underground works runs into the Mariposa creek and it is used by cattle and through filtration by human consumption.

Both NCM and Meridian reported fast and easy fulfilled requirements to obtain the necessary environmental permits for exploration and infrastructure developments.


5.0 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

5.1 Accessibility

Access to the Guadalupe de Los Reyes Project area is from approximately midway (100 kilometers) on the toll road that connects the cities of Mazatln, and Culiacn of the State of Sinaloa, and then to Cosal by a 55-kilometer, two-lane paved highway. From Cosal to the project area is a 30-kilometer dirt road. An airstrip for small aircraft is located near Cosal, with public and private service to the cities of Mazatln, Culiacn and Durango.

5.2 Climate and Physiography

The Guadalupe de Los Reyes Project is located in the western foothills of the Sierra Madre Occidental at elevations that vary from approximately 300 meters to 1,000 meters. The topography is moderate to rugged; however, it is increasingly rough towards the core of the mountain range at elevations that reach over 3,000 meters.

Climate in this area is arid to semi-arid with an average temperature of 22 to 26C and an average rainfall of approximately 1,000 millimeters, which occur mostly during the period of June to September in strong storm events that cause flooding along the river beds and frequent interruptions of the road to Cosal. Moderate to dense vegetation of bushes and shrubs covers the hill slopes within the Project area, in a transition zone that changes from the tropical vegetation towards the lower elevations and that of evergreens and other types of trees at higher topography. Most of the people living in the villages of the area depend on small scale farming, raising livestock, and growing fruit.

5.3 Local Resources and Infrastructure

The city of Cosal constitutes the commercial center for the population living in small villages and scattered settlements located on ejidos (land communities) around the Guadalupe de Los Reyes mining district. The road from Cosal through Guadalupe de Los Reyes is the only regional access to the mountains to the east in this part of the Country. Cosal offers retail, banking, medical, educational, hospital, and communications to the rest of the Country; however, major facilities are located in the cities of Mazatln and Culiacn.


6.0 HISTORY

The Guadalupe de Los Reyes mining district was discovered, according to local residents on December 12, 1772 (virgin of Guadalupes day) and claimed on January 6, 1773 (Wise mens day, da de los Reyes Magos); hence the current name of Guadalupe de Los Reyes (previously Guadalupe Los Reyes) Several areas were developed within the district throughout its production history, mainly the Guadalupe mine, El Zapote, San Miguel, Mariposa, La Chiripa, Tahonitas, Noche Buena, Candelaria, Tatemas, Las Primas, and Fresnillo, along three principal vein systems. These veins include the 2.5-kilometer long East-West system of the Guadalupe mine; 4.0-kilometer long NW-trending systems of San MiguelChiripaNoche Buena, and MariposaZapote-Tahonitas, and other secondary systems. Intermittent production of gold/silver ores from the different mines within the district was reported until the 1950s. Access to the district was on horse back until the early 1960s when the dirt road access from Cosal was finally built.

Historical production for the Guadalupe de Los Reyes district was estimated in February 1936 by Mr. C. W. Vaupell as approximately 600,000 ounces of gold and over 40 million ounces of silver (1.5 million tones of ore averaging 12 g/t Au and 900 g/t Ag). A more comprehensive report, based on National Registry records, by Minas de San Luis, S.A. de C.V. summarized the production as indicated in Table 6-1.

Other areas within the district have produced additional amounts of precious metals in lower scale. Total reported production and grades for the district result in a more conservative amount of approximately 320,000 ounces of Gold and 15.00 million ounces of Silver, in addition to previous unknown production for the period of 1772 to 1871.

From the middle of the 1950s to the 1980s there was limited activity within the Guadalupe Los Reyes district that included exploration reconnaissance studies and mining concessions promotions, until NCM took important steps to test the geologic potential with drilling and considerable investments in the early 1990s.

TABLE 6-1 Vista Gold Corporation Summary of Production (*) Guadalupe Los Reyes Mining District

Mine Period Years Metric Tonnes Average Grade Gold

Average Grade Silver

Guadalupe Los Reyes 1772 1871 Unknown Unknown Unknown Guadalupe Los Reyes 1872 - 1938 874,658 8.80 521 Minera Tatemas 1935 - 1944 170,000 12.00

Operating companies in the district included Negociacin Minera de Guadalupe de los Reyes, S.A.; Compaa La Chiripa y Anexas; Compaa Candelaria Canoas, S.A., and in recent times Mr. Enrique Gaitn Enrquez representing various companies as Compaa Minera Campanillas, S.A. de C.V., Minera Tatema, S.A. de C.V., and Minera Sierra Pacfico, S.A. de C.V., and Minera Mariposa, S.A. de C.V.; and most recently exploration companies as Minas de San Luis, S.A. de C.V. (Tayoltita mine); Minera Silverado, S.A. de C.V.; Northern Crown Mines Ltd.; Meridian Gold Company; and now Vista Gold Corporation.


7.0 GEOLOGICAL SETTING

The following discussion of geology is based on information provided by NCM in a report entitled Exploration Report On The Guadalupe de los Reyes Property, Mexico, dated October 1996, in a report by Messrs. Gordon J. Allen, P. Geol. and Brian G. Thurston on behalf of NCM, Report on the Exploration Programs on the Guadalupe de los Reyes Property, of December 1997, in previous report, Conceptual Report on the Mariposa Deposit of June 1992 by PAH, in data presented in PAHs Prefeasibility Study of January 28, 1998, and in PAH=s observations during several visits to the site, including the most recent site visit of may 20 to May 22, 2003.

7.1 Guadalupe de Los Reyes Project Regional Geologic Setting

The Guadalupe de Los Reyes Project occurs in the Sierra Madre Occidental Province, a late Cretaceous to Tertiary age volcanic sequence that extends for hundreds of kilometers from the Neo-Volcanic Belt in central Mxico to the Basin and Range Province in the northern part of the country. In the project area, the volcanics rest unconformably or in fault contact with a basement of late Cretaceous age quartz monzonite intrusive (Batholith of the Coast) that intrudes older platformal sediments. The overlying volcanic sequence has been divided into two groups, the late Cretaceous to early Tertiary age Lower Sequence and the middle Tertiary (Oligocene-Miocene) age Upper Volcanic Sequence. The Lower Volcanic Sequence is up to 1,000 meters thick and consists of tuffs, flows, and volcanic breccias of andesitic to dacitic composition. Thick beds of sandstone and volcanic conglomerate occur intercalated in the sequence. The Upper Volcanic Sequence rests unconformably upon the lower sequence. The Upper Volcanic Sequence consists of gently dipping, ash-flow and ash-fall tuffs of rhyolite to dacite composition. The unit is more than 1,000 meters in thickness but has been largely removed by extensive erosion. Figure 7-1 shows the Guadalupe de Los Reyes geologic setting, noting the identified mineral deposits.

A period of tectonism, intrusion and mineralization occurred between the deposition of the early Tertiary Upper Volcanic Sequence and middle Tertiary Lower Volcanic Sequence, as evidenced by the variable angular unconformity between the two units. Uplift and faulting of the region was accompanied by the intrusion of felsic to mafic composition dikes, along with the local emplacement of intrusive stocks. Structural zones formed from faulting of the Lower Volcanic Sequence were locally mineralized with quartz veins containing gold and silver. No significant mineralization is found in the Upper Volcanic Sequence within the Project area.

In the project area, gold and silver mineralization has been found along a series of northwesterly and west-northwesterly structural zones. Mineralization in these zones is typical of low sulfidation epithermal systems. Eight main target areas have been identified by NCM and by old mining workings along three major structural zones. Several of these targets have bulk tonnage potential which may be amenable to open-pit mining, including the El Zapote, San Miguel, Guadalupe Mine, Tahonitas, and Noche Buena zones. The El Zapote zone, occurs in the Mariposa-El Zapote-


Prepared by

PINCOCK, ALLEN & HOLT274 Union Boulevard, Suite 200Lakewood, Colorado 80228Phone (303) 986-6950

Project No.

Project Name

FIGURE 7-1

GEOLOGY MAP - GUADALUPE DE LOS REYES AREA

Date of Issue

Drawing Name

9203.04

June/2003

Fig7-1.cdrGuadalupe de Los Reyes Project

Prepared for

VISTA GOLD CORP.

GRANODIORITE

Lower Volcanic SequenceANDESITE

PORPHYRYSTOCK

DACITEDOME

GuadalupeMine Zone

Structures HostingGold-Silver Mineralization

San MiguelChiripa Zone

Las PrimasZone

Noche BuenaZone

FresnilloZone

TahonitasZone

ZapoteZone

MariposaZone

N

5000

Scale in Meters

1000

Upper Volcanic SequenceRHYOLITE



DACITEDOME

DACITEDOME

DACITEDOME

Tahonitas structural zone on the western side of the project area and has been mapped for a distance of 3 kilometers. The El Zapote deposit is one of three deposits found along this structural zone, with the inactive underground Mariposa Mine 1 kilometer to the northwest and the Tahonitas prospect 0.5 kilometers to the southeast. The Guadalupe zone occurs as the northwest extension of the mineralized structures that were developed by underground mining along approximately 1000 meters of the veins and to some 400 meters depth. The Guadalupe zone is found in the northeast portion of the area and has produced the majority of precious metals within the district. The San Miguel and Noche Buena zones are enclosed by the same northwestern trending structure in between the El Zapote- Mariposa and the Guadalupe structures.

7.2 El Zapote Deposit Geology

The El Zapote deposit occurs along a regional structural zone that dips approximately 50 degrees to the southwest and offsets eastward dipping rocks of the Lower Volcanic Sequence (Figure 7-2). The structural zone consists of sheared and brecciated volcanic rocks that have been intruded by felsic dikes and then, subsequently, mineralized by hydrothermal solutions. The deposit mineralization extends for approximately 1 kilometer in a northwest-southeast direction along the structure.

The El Zapote deposit has been intercepted by drilling to approximately 200 meters down dip. Drilling has found that the deposit thickness ranges from a few meters to several tens of meters. The deposit occurs in two zones, the North (northwest) zone and the South (southeast) zone, separated by an area of limited mineralization.

The more intensely mineralized part of the El Zapote structural zone typically occurs towards the base of the zone and consists of several meters of quartz veining along with intensely silicified breccia. Alteration and mineralization into the footwall volcanics of the structural zone is limited to a few meters at most and typically consists of weak silicification and/or propylitic alteration. Alteration and mineralization into the hanging wall volcanics, however, extends over many meters to tens of meters and is gradational vertically into the unaltered host volcanic sequence. The hanging wall zone consists of variable quartz veining, silicification and brecciation, along with moderate argillization.

Gold and silver mineralization in the El Zapote deposit are associated with strong silicification. Silicified zones consist of quartz (+ calcite, adularia) veins and veinlets, along with tectonic breccia unfilled by chalcedonic silica. Gold and silver are typically present as microscopic (tens of microns) sized particles of native gold, electrum, and minor argentite. Locally, higher-grade fire assays with erratic results suggest the minor presence of coarser gold, causing a larger nugget effect (i.e. ZA-068 at 47.24 meters, ZA-069 also at 47.24 meters, and ZA-102 at 35.05 meters). Minor pyrite is rare, originally averaging less than 0.5 percent of the vein volume. Surface oxidation has variably transformed the original pyrite into iron oxides to depths of tens of meters below the surface. As the gold largely occurs as microscopic-sized, free to quartz-encapsulated particles, the oxidation of the pyrite does not appear to be a major factor in metallurgical gold liberation and recovery, although some downward decrease in recovery was observed in bottle roll tests and should be


investigated further. The silver to gold ratio in the deposit is approximately 15:1, based on total silver to total gold (fire assay). This zone was explored with 197 reverse circulation holes (15,728 m).

7.3 Guadalupe Mine Deposit

The Guadalupe mine area is enclosed by an east-southeast trending mineralized structure that extends over 2.5 kilometers by up to 100 meters in width; it is composed of two main veins, Guadalupe and San Manuel with stockwork and numerous quartz veinlets in between. The Guadalupe Mine zone presents a southwest steep dip and was developed by underground methods to a depth of some 400 meters, 10 - 13 production levels, along a strike length of approximately 1000 meters. Historic recorded production for the mine was estimated at 874,658 tonnes with an average grade of 8.8 g/t gold and 521 g/t silver, comprising over 70 percent of the districts recorded gold production, in addition to some unrecorded earlier production.

The Guadalupe mineralized structure is enclosed by volcanic rocks of the Lower Volcanic Sequence, which dip gently eastward and consists of andesitic flows and tuffs. This area was divided into three sections for exploration purposes, Guadalupe West, Laija and East. It was drilled with 78 reverse circulation holes totaling 10,547 meters. Figure 7-3 shows a vertical section of the Guadalupe Mine development, while Figure 7-4 presents cross section 4900 of the Guadalupe Laija deposit showing some of the old underground workings of the Guadalupe and San Manuel veins within the Guadalupe structure and representative drilling results.

7.4 Chiripa - San Miguel Noche Buena Deposits

The San Miguel deposit is enclosed by the Chiripa - San Miguel Noche Buena mineralized structure. It consists of a northwest trending fault system dipping 50-60 to the southwest. It has been traced for a distance of 1.4 kilometers and tested with some stopes, trenches and adits. NCM carried out a reverse circulation drilling program that included 33 holes and a total of 3,674.35 meters in the San Miguel Chiripa zone, in addition to the 37 holes with 4,070.81 meters drilled in the Noche Buena zone.

The Chiripa - San Miguel structure is enclosed by andesitic rocks of the Lower Volcanic Sequence, which appear to be intruded by an argillic altered, feldspar-horblende-biotite porphyry dike. Mineralization is associated with the brecciated zones along the structure and in proximity to the dike, with apparent concentration at the footwall. Figure 7-5 shows cross section 5150 of the San Miguel deposit.

The Noche Buena deposit constitutes the southern extension of the San Miguel zone, and it is enclosed by the same mineralized structure. It consists of a system of sub-parallel quartz veins and veinlets recognized along 550 meters of strike and 3 to 30 meters in width. Figure 7-6 presents cross section 4600 of this deposit.


WEST

LAIJA

Gold - SilverMineralization

Prior Recorded Production247,500 Ounces Gold

14.7 Million Ounces Silver

Prepared by


Project No.

Project Name

FIGURE 7-3

GUADALUPE MINE - UNDERGROUND DEVELOPMENT

Date of Issue

Drawing Name

9203.04

June/2003


Prepared for

VISTA GOLD CORP.

7.5 Tahonitas Deposit

The Tahonitas deposit occurs along the southeast extension of the El Zapote mineralized structure. It is enclosed by andesitic rocks of the Lower Volcanic Sequence and it is capped at its eastern most end by rhyolite and aplites of the Upper Volcanic Sequence. The mineralized structure at Tahonitas presents a northeast trend dipping 45 to 60 to the southwest. A felsic rock intrusive is emplaced along the structure that cuts the andesitic rocks in up to several tens of meters creating appropriate conditions for emplacement of the quartz veins. It has been recognized along 900 meters of strike with 5 to 25 meters in width. It was explored by NCM with 33 reverse circulation holes for a total drilling of 2,257.98 meters. Please refer to cross-section 4650 in Figure 7-7 that shows the Tahonitas vein.


8.0 DEPOSIT TYPES

Mineralization in the Guadalupe de Los Reyes area is typical of low sulfidation epithermal gold/silver systems. Eight main deposits have been identified by NCM and other operators along three major structural zones. Several of these deposits have bulk tonnage potential which may be amenable to open-pit mining, including the El Zapote, San Miguel, Guadalupe Mine, Tahonitas, and Noche Buena zones.

Epithermal deposits of low sulphidation type such as those found in the Guadalupe de Los Reyes Project area generally form within predominately felsic subaerial volcanic complexes in extensional and strike-slip structural regimes. Near-surface hydrothermal systems including surface hot springs and deeper hydrothermal fluid-flow zones are the sites of mineralization. Mineral deposition takes place as the fluids undergo cooling by fluid mixing, boiling and decompression.

An illustration of a typical epithermal system is shown in Figure 8-1.


Prepared by


Project No.

Project Name

FIGURE 8-1

EPITHERMAL MODEL

Date of Issue

Drawing Name

9203.04

June/2003


Prepared for

VISTA GOLD CORP.

9.0 MINERALIZATION

In the Guadalupe de Los Reyes project area, gold and silver mineralization has been found along a series of northwesterly and west-northwesterly structural zones. Mineralization in this area is typical of low sulfidation epithermal systems consisting of quartz-adularia veins and stockwork zones. The gold and silver minerals are associated with the quartz. It appears that two stages of silification occur within the area; the first stage brought a commonly banded quartz, typically of a pale yellow-green color, while the second consisted of white crystalline quartz. It appears that the gold and silver minerals are most commonly associated with the first stage yellow-green chalcedonic quartz. Mineralization in the Project occurs in an area that covers approximately 5.0 by 2.0 kilometers (1,000 hectares), however, the mineralized structures and anomalies have been extended by geologic interpretations to an area of over 8,600 hectares (21,250 acres).

In thin section studies of the host rocks, andesite to felsite are variably altered showing plagioclase converted to potassic feldspar. In many instances the host rock is completely replaced by fine-grained quartz or sericite with relatively abundant adularia. Gold occurs as grains that range from 5 to 30 and up to 230 microns (0.23 mm) in diameter. Free gold and silver minerals are observed associated to quartz veins and in patches of sericite. Fine grains of pyrite occur typically oxidized to limonite or hematite in volume estimated at less than 0.5 percent.

Alteration consists predominantly of silicification and sericitization. Silicified volcanic rocks typically show partial to complete replacement of the original components by fine-grained quartz. Typical silicification of the enclosing rocks grades from complete replacement by quartz to partial silicification, from the footwall of the structures towards the hanging wall into stockworks and less dense veining with presence of chlorite and pyrite in an incipient propylitic alteration.

Weathering and a low volume of sulphide minerals within the deposits have caused no known problems of contamination in runoff waters from the mining zones.

Table 9-1 presents a summary of the known extent of the various mineralized zones of the Guadalupe de Los Reyes project. Figure 9-1 shows Vista optioned claim coverage, the geologic model areas, and drill hole locations for each of the identified deposits.


TABLE 9-1 Vista Gold Corporation Guadalupe de Los Reyes Project General Deposit Data

Deposit Explored Extension General Characteristics El Zapote Length: 1,000 meters.

Width: 20 meters (5 to 50 m). Depth: 150 meter, open to depth. Drilling: 20 40 meter spacing (30 m), 204 holes. Resources: Within quartz zone and veins.

Structure: El ZapoteTahonitasMariposa. Strike: NW . Dip: 50 to W. Contacts: Sharp footwall contact and stockwork to the hanging wall.

Tahonitas Length: 750 meters. Width: 10 meters (5 to 25 m). Depth: 125 meters, open to depth. Drilling: 33 holes at 50-m spacing. Resources: Within quartz veins and quartz stringers. Open to further investigation.

Structure: Southern extension of the El ZapoteTahonitasMariposa. Strike: S 30 E. Dip: 45 to 60 to the SW. Contacts: Sharp footwall, some veining to the hanging wall.

San Miguel Length: 1,400 meters. Width: 15 meters. Depth: 70 meters, open to depth. Drilling: 39 holes at 70-m spacing. Resources: Within veins and stockwork. Open to further investigation.

Structure: San Miguel Noche BuenaChiripa. Between the El Zapote and Guadalupe structures. Strike: S70E. Dip: 70 to the SW. Contacts: Sharp both walls.

Noche Buena Length: 1,100 meters. Width: 14 meters (3 to 30 m). Depth: 100 meters, open to depth. Drilling: 25 holes at 50-m spacing. Resources: Within quartz zone and stockworks. Open to further investigation.

Structure: San Miguel-Noche Buena-Chiripa, in SE extension. Strike: S30E. Dip: 50 to 60 to the SW. Contacts: Sharp footwall and stockwork to the hanging wall.

Guadalupe Length: Developed by underground mining along 1,250 meters. Structure is 2,500 meters long. Width: 2-3 m veins, within mineralized structure of 100 m. Depth: Developed to 400 meters. Drilling: 87 holes in extensions to the NW and to the SE at the Laija zone. Spaced at 50-70 m. Resources: Two main (2 3 m) veins within the structure and stockworks, open to further investigation.

Structure: Guadalupe mine. Strike: S 80-70E. Dip: 65 to 90 to SW. Contacts: Sharp in veins within breccia zone, extensions to the NW of the old workings and to the SE, Laija.


10.0 PROJECT EXPLORATION

Gold and silver production in Guadalupe de Los Reyes began in 1772 when the Guadalupe vein was discovered. Intermittent production for a period of 150 years, to the 1950s has resulted in a reported accumulated extraction of approximately 1.1 million tones with an average grade of 9.20 g/t gold and 430 g/t silver from the various deposits located within the mining district. Between October 1988 and February 1989, Enrique Gaitn and Associates mined 31.5 thousand tonnes with a reported grade of 5.8 g/t Au from an open cut in the El Zapote South area and recovered, according to Mr. Gaitn, approximately 93 kilograms of gold from a small cyanide vat leach facility. Minera Sierra Pacfico, a wholly-owned subsidiary of NCM began conducting exploration activities in the El Zapote area in 1992, when modern methods of exploration were first applied in the Project with a program that included geochemical soil and rock chip sampling, geophysical with VLF-EM and Magnetic studies, drilling, sample and assay checks, partial underground development, and computer modeling to estimate mineral resources. Preliminary metallurgical test work was carried out on bulk samples and drill chips from the El Zapote deposit. Environmental permits for exploration works have been obtained by NCM and Meridian.

NCM, under an option to purchase the mining claims that covered all the Guadalupe de Los Reyes District, developed a full program of exploration, part of which was reported in a Prefeasibility Report prepared by the consulting firm of PAH. The exploration program included drilling five zones within the Guadalupe district as follows:

El Zapote deposit, 197 RC holes, 15,728 meters Guadalupe deposit, 78 RC holes, 10,547 meters San Miguel deposit, 33 RC holes, 3,674 meters Noche Buena deposit, 37 RC holes, 4,071 meters, and Tahonitas deposit, 33 RC holes, 2,258 meters

In December 2001 Meridian optioned the project from NCM and carried out Due Diligence investigation including sample checks and drilling of 23 additional confirmatory holes in four areas as follows:

El Zapote deposit, 5 RC holes, 829.3 meters La Chiripa deposit, 9 RC holes, 829.2 meters San Miguel deposit, 6 RC holes, 698.2 meters, and Orito deposit, 3 RC holes, 375.0 meters

Meridian subsequently dropped the option with NCM in 2002. In December 2002 NCM returned all mineral rights for the Guadalupe de Los Reyes project to the original concessionaires, including


Mr. Enrique Gaitn, Minas de San Luis, Minera Mariposa, and a group of concessionaires from the city of Culiacn.

In January 2003 Vista Gold Corp. entered an agreement to acquire 100 percent of the mineral rights held by Mr. Gaitn, which cover approximately 7 percent of the Guadalupe de Los Reyes mining district area with a total of 596.9780 hectares (1,475.1326 acres). These concessions enclose most of the main identified exploration targets within the Guadalupe de Los Reyes district area, including approximately 73 percent of the El Zapote deposit gold resources, all of the Guadalupe-Laija deposit, 2.6 percent of the Guadalupe-West deposit, 25 percent of the Chiripa-San Miguel deposits, all of the Noche Buena deposit, and 99 percent of the Tahonitas deposit. Please refer to Figure 9-1.


11.0 PROJECT DRILLING

Exploration of the Guadalupe de Los Reyes Project by NCM, Meridian and other companies has consisted of geological, geochemical, geophysical studies, and exploration drilling. Total drilling within the project area to date consists of 398 holes, for a total of 38,837.81 meters and 23,938 sample intervals assayed. Drilling has been conducted exclusively by reverse circulation methods. Air circulation was used primarily to recover chips from the hole, but where ground water was occasionally encountered, water recovery was used to move the cuttings out of the hole. Earlier drill hole collar locations were only surveyed by chain and compass, while later drill hole collar locations were surveyed by differential global positioning systems (GPS) with less than 1meter accuracy. Those earlier drill holes that were still locatable were subsequently surveyed by GPS as well.

PAH conducted a comprehensive review of NCM drill methodology during the Prefeasibility Study, including control, registry and sampling processes. After incorporating drill data from Meridian, a total holes correlation of drill collar elevation to model topography was developed to test the reliability of the elevations in the database. The El Zapote results indicate that 95 percent of NCM drill collars correlate between a range of 10 to +10 meters, an acceptable range, while Meridians data resulted in 80 percent within a range of 17 to 30 meters with respect to the topographic model. Anomalous hole collars for the El Zapote deposit are for the ZA holes 197, 104, 173, 171, 175, 188, 182, 178, 187, 168, and 169 and the Meridian series GZ holes 01, 02, 04, and 03. Drilling at San Miguel Chiripa zones resulted in 94 percent of NCM collars within a range of 10 to +10 meters with respect to the topographic model, while 40 percent of Meridian holes fall within 21 to 35 meters from the topographic model. At the Guadalupe Laija deposit, NCM drill holes GL-046 and GL-045 show anomalous negative differences with respect to the topography, while the NCM holes GS-056, GL-069, GE-030, GL-053, GE-074, and GE-078 show differences greater than 10 meters. PAH suggests that the indicated NCM and Meridian hole collars be checked to ensure that they are correctly entered in the data to properly represent mineral and structural intercepts. Figure 11-1 presents correlation of collar to topography for the El Zapote deposit, Figure 11-2 shows the correlation for the Chiripa-San Miguel deposits, and Figure 11-3 presents the correlation of collar to topography for the Guadalupe Laija deposit.

During the most recent site visit to the project area, PAH performed a GPS check of some of the Meridian drill hole locations (hand held GPS Garmin, Model eTrex Vista) which resulted in close readings for East and North coordinates; however, the average GPS elevation for holes in the San Miguel and Chiripa zones represented an average difference of approximately 27 meters. The highest difference resulted in 36 meters (GS-05 and GS-06), and the lowest was reported at 18 meters (GC-01 and GC-02) as compared to the data reported from Meridian. Please refer to Table 11-1.


-20

-15

-10

-5

0

5

10

15

20

25

1 6

11

16

21

26

31

36

41

46

51

56

61

66

71

76

81

86

91

96

10

1

10

6

111

11

6

12

1

12

6

13

1

13

6

14

1

14

6

15

1

15

6

16

1

16

6

17

1

17

6

18

1

18

6

19

1

19

6

Series1

# Drillholes

Topo +\-Mete

rs

MeridianHoles

Prepared by


Project No.

Project Name

FIGURE 11-1

CORRELATION COLLAR/TOPOGRAPHYEL ZAPOTE DEPOSIT

Date of Issue

Drawing Name

9203.04

June/2003


Prepared for

VISTA GOLD CORP.

-40

-35

-30

-25

-20

-15

-10

-5

0

5

10

15

1 3 5 7 9

11

13

15

17

19

21

23

25

27

29

31

33

35

37

39

41

43

45

47

49

Series1

# Drillholes

Topo +\-

Mete

rs

MeridianHoles

Prepared by


Project No.

Project Name

FIGURE 11-2

CORRELATION COLLAR/TOPOGRAPHYCHIRIPA - SAN MIGUEL DEPOSITS

Date of Issue

Drawing Name

9203.04

June/2003


Prepared for

VISTA GOLD CORP.

-10

-5

0

5

10

15

201 3 5 7 9

11

13

15

17

19

21

23

25

27

29

31

33

35

37

39

41

43

45

47

49

51

53

55

57

59

61

63

# Drillholes

Topo +\-

Mete

rs

Prepared by


Project No.

Project Name

FIGURE 11-3

CORRELATION COLLAR/TOPOGRAPHYGUADALUPE LAIJA DEPOSIT

Date of Issue

Drawing Name

9203.04

June/2003


Prepared for

VISTA GOLD CORP.

TABLE 11-1 Vista Gold Corporation Data Verification Meridian Drill Hole Locations AREA MERIDIAN GPS READING PAH % DIFFERENCE LOCATION EAST NORTH Elev. M EAST NORTH Elev. M Eastings Northings Elevations San Miguel GS-01 345276 2685076 690 345274 2685069 663 0.00 0.00 -3.91 GS-02 345276 2685073 690 345274 2685069 663 0.00 0.00 -3.91 GS-03 345215 2685024 715 345212 2685031 681 0.00 0.00 -4.76 GS-04 345218 2685032 715 345212 2685031 681 0.00 0.00 -4.76 GS-05 345268 2684940 730 345266 2684943 694 0.00 0.00 -4.93 GS-06 345274 2684942 730 345266 2684943 694 0.00 0.00 -4.93 Chiripa GC-01 344106 2685280 757 344107 2685277 739 0.00 0.00 -2.38 GC-02 344104 2685280 757 344107 2685277 739 0.00 0.00 -2.38 GC-03 344396 2685304 723 344395 2685302 704 0.00 0.00 -2.63 GC-04 344393 2685309 723 344395 2685302 704 0.00 0.00 -2.63 GC-05 344393 2685306 723 344395 2685302 704 0.00 0.00 -2.63 GC-09 344503 2685315 738 344508 2685306 703 0.00 0.00 -4.74 Average -3.72%

Most of the reverse circulation holes were drilled with inclined holes to better test the dipping mineralization. At the El Zapote deposit, drill hole locations are irregularly placed on lines that are spaced at approximately 25 meters. Drill hole spacing at El Zapote along the lines ranges from 20 to 40 meters and averages approximately 30 meters. PAH finds that the drill hole spacing in this case is adequate for establishing a reasonable degree of confidence necessary for defining resources. Geostatistical results from variograms for the gold deposits suggest ranges of up to 40 meters. SRK reported insufficient data available for silver to generate reasonable variogram models. Drilling at other deposits within the project area were spaced at approximately 50 meters for Guadalupe-Laija, Chiripa, Noche Buena and Tahonitas, and at 70 meters for the Guadalupe-West and San Miguel. Figure 11-4 shows drill locations for El Zapote-Tahonitas and Chiripa deposits; Figure 11-5 San Miguel and Noche Buena, and Figure 11-6 Guadalupe (Laija and West).

PAH notes that the drill holes in the database were not surveyed for directional deviation down the hole when they were drilled. Although this is not necessarily a problem, the drill holes may have deviated from the planned direction and dip, particularly in deeper holes, resulting in mineralized intercept locations potentially being displaced from their actual locations. As most of the project drilling is relatively shallow (50-100 meters), this is not likely to be a significant problem.

Table 11-2 shows a summary of drilling and sample assays collected by NCM and Meridian. Sample length typically was 1.52 meters per sample.


TABLE 11-2 Vista Gold Corporation Guadalupe de Los Reyes Project Drilling and Drill Samples Assayed (1)

Deposit El Zapote Guadalupe San Miguel Noche Buena

Tahonitas El Orito Mariposa TOTAL

Northern Crown Mines

RC No. Drill Holes 197 78 33 25 33 8 1 375

Meters Drilled 15,728.14 10,547.00 3,674.35 2,592.55 2,257.98 1,139.97 166.12 36,106.11

Drill Samples Total 10,234 6,899 2,361 1,671 1,449 748 106 23,468

Meridian Gold Inc.

RC No. Drill Holes 5 9 6 0 0 3 0 23

Meters Drilled 829.3 829.2 698.2 0 0 375.0 0 2,731.7

Drill Samples Total (*) 378 9 39 0 0 6 38 470

Total Project Drilling and Assaying

RC Holes Total 202 87 39 25 33 11 1 398

Meters drilled Total 16,557.44 11,376.20 4,372.55 2,592.55 2,257.98 1,514.97 166.12 38,837.81

Drill Samples Total 10,612 6,908 2,400 1,671 1,449 754 144 23,938

(1) Summary of Exploration Work by Gordon J. Allen. * Meridian partial data available.


12.0 SAMPLING METHODOLOGY

PAH reviewed NCM=s reverse circulation hole sampling program for the preparation of the Prefeasibility Report of January 1998. The sampling program consisted of collecting samples at 1.52-meter intervals (5 feet) from 133 mm (5.2- inch) diameter holes. Samples were collected from the cyclone into collection buckets. Dry samples were split using a Jones riffle splitter, and wet samples were split using a rotary splitter. A 5-kilogram split (approximate) was placed into a plastic sample bag for laboratory analysis. Fifteen to twenty kilograms of the remaining material was placed in a second sample bag and saved as the field duplicate. In a similar manner Meridian sampling was described as collecting samples at 1.52-meter intervals. The lithology, alteration, and mineralization were recorded on site for each sample. Table 12-1 shows the number of geochemical soil and rock chip samples, and RC drill cutting samples taken by NCM and Meridian in the Guadalupe de Los Reyes mineralized zones.

TABLE 12-1 Vista Gold Corporation Guadalupe de Los Reyes Project RC Hole Cutting Samples and Geochemical Sampling

DEPOSIT Geochemical Soil

Geochemical Rock(*)

No. RC (1) Drill Samples

El Zapote 151 105 10,612 Guadalupe 1,134 422 6,908 San Miguel 513 339 2,400 Noche Buena 314 111 1,671 Tahonitas 512 80 1,449 El Orito 564 64 754 Mariposa 651 212 144 Other Zones 621 115 0 TOTAL 4,460 1,448 23,938 (*) It does not include underground sampling. (1) NCM plus Meridian samples

Metallurgical test work was completed for three bulk samples collected from the Zapote deposit. Sample A (Zapote Saddle Sample) consists of strongly silicified/quartz vein material that initially ran 7.83 g/t Au and 32.6 g/t Ag. Sample C (Gaitn Footwall Sample) consists of strongly silicified/quartz vein material near the footwall of the structural zone in a small excavation known as the Gaitn Cut; the initial sample analysis ran 2.42 g/t Au and 34.3 g/t Ag. Sample D (Gaitn Stringer Sample) consists of strongly silicified/quartz vein material in the gradational hanging wall of the structural zone in the Gaitn Cut. The initial sample analysis ran 1.37 g/t Au and 50.1 g/t Ag. All three samples are from relatively shallow depths that would have been subjected to some oxidation effects; however, NCM was not able to find any marked changes in oxidation with depth that might indicate recovery changes. Additionally, eight composite samples from reverse circulation drill hole cuttings were prepared to conduct metallurgical bottle roll test work; these were taken


from remains of the mineralized sections of some of the El Zapote deposit holes as indicated in Table 12-2.

Density measurements were made by NCM on reverse circulation drill hole samples representing both the mineral envelope and the adjacent volcanic host rocks. A total of 1,352 density tests were made from samples collected at approximately every fifth sample interval of the 1997 drilling (ZA-088 to ZA-197). The density results on these cutting samples indicated a density of 2.6 grams per cubic centimeter (equivalent to tonnes per cubic meter). The subsequent resource is calculated on the basis of this density factor. PAH notes that these density results based on chip samples would tend to be higher (more dense) than actual bulk tonnage because fracture and void space is not adequately accounted for. Subsequent test work from McClelland on 16 samples from the surface metallurgical bulk samples found that the bulk tonnage averaged 2.44 tonnes per cubic meter. PAH recommends that the bulk density value be further substantiated in the future by samples at depth from core sampling.

TABLE 12-2 Vista Gold Corporation Guadalupe de Los Reyes Project RC Hole Cutting Samples for Metallurgical Testwork (*)

Composite No. Hole Samples Interval meters Gold g/t Silver g/t ZPF 01 ZA-077, 159. 36.28 1.85 11.40 ZPF 02 ZA-073, 078. 65.54 1.53 8.90 ZPF 03 ZA-168, 176. 41.15 1.25 10.70 ZPF 04 ZA-087, 147, 150. 27.44 1.35 12.30 ZPF 05 ZA-092, 113. 13.72 0.75 13.20 ZPF 06 ZA-102, 108, 109. 19.81 1.05 20.80 ZPF 07 ZA-088, 095, 096. 32.00 1.06 9.40 ZPF 08 ZA-089, 123. 20.89 1.82 20.10

(*) Head samples assayed by fire fusion procedures. McClelland Labs.


13.0 SAMPLE PREPARATION, ANALYSIS AND SECURITY

PAH conducted a thorough review of NCM sampling procedures and lab processing for the Prefeasibility Study of January 1998. Most of the project analytical samples were delivered to Bondar-Clegg de Mexico, S.A. de C.V. (Bondar-Clegg) in Hermosillo, Mxico for sample preparation. PAH noted, however, that during one period (drill holes ZA-016 to ZA-053 or approximately 20 percent of the data) analyses were conducted by SGS-XRAL laboratories in Hermosillo, Mxico. At Bondar-Clegg, the entire sample was crushed to 75 percent passing 10 mesh using jaw and cone crushers. Representative 250-gram splits of the crushed sample were obtained using a Jones riffle splitter. These splits were then pulverized to -150 mesh using a ring and puck pulverizer. The resultant samples where sent to Bondar-Cleggs=s assay laboratory in Vancouver, British Columbia, for gold and silver analysis. For gold, a one assay ton fire assay was conducted with an atomic absorption finish, and, if the atomic absorption value exceeds 10 g/t Au, then it was reassayed with a gravimetric finish. PAH notes that this is a typical analytical protocol and that Bondar-Clegg is an internationally recognized laboratory.

Silver analyses of earlier drill hole samples were conducted by fire assay with an atomic absorption finish, if silver was analyzed at all. Later drill hole samples in which silver was routinely analyzed was largely conducted by aqua regia digestion followed by atomic absorption. The acid digestion/atomic absorption silver values have been found to consistently be lower than the fire assay values because of a less complete extraction of the silver from the samples. This is not a problem as long as the basis for the silver analyses is stated when applying metallurgical recoveries. Silver analyses by acid digestion/atomic adsorption were used for the resource calculations.

NCM had approximately 10 percent of the sample intervals in the mineralized zone sent for duplicate analysis by a second laboratory to evaluate the quality of the sample analyses. Check assay data is shown in Figure 13-1. Check analyses were conducted for the 1997 drilling program (ZA-088 to ZA-197) and for the 1996 drilling program (ZA-066 to ZA-087). For this work, Bondar-Clegg supplied the sample pulps to Min-En Laboratories (Min-En) in Vancouver, British Columbia. Min-En reportedly analyzed the sample pulp material utilizing similar methodology as described by Bondar-Clegg.

Statistical evaluation by PAH of the 1997 drilling program found an acceptable correlation between the data pairs, with a lognormal correlation coefficient of 0.98 (out of 1.00). Overall, the variance between most sample-duplicate pairs was + 30 percent and is typical of structural zone gold deposits. There was, however, a tendency on the part of several samples for the Bondar-Clegg analysis to be significantly higher than that from Min-En and should be investigated further. However, a comparison of the average grades found that the Bondar-Clegg originals were about 5 percent lower than the Min-En duplicates, a difference that is acceptable by normal engineering practice.


PAH found that for the 1996 drilling program, the correlation of the data pairs showed less correlation with a lognormal correlation coefficient of 0.94 (out of 1.00). Overall, the variance between most sample-duplicate pairs was + 20 percent. PAH noted that there was still a tendency on the part of several samples for the Bondar-Clegg analysis to be significantly higher than that from Min-En. A comparison of the average grades of the sample pairs found that, contrary to the 1997 drilling, the Bondar-Clegg originals were 10 percent higher than the Min-En duplicates. PAH believes that a 10 percent difference is the limit of what is acceptable by normal engineering practice.

Check analyses were also conducted on material from earlier drilling programs between 1992 and 1995 (ZA-016 to ZA-065), with original analysis largely by SGS-XRAL laboratory for drill holes ZA-016 to ZA-053 and to a lesser extent by Bondar-Clegg for drill holes ZA-054 to ZA-065, with the duplicate checks conducted by Bondar-Clegg. PAHs evaluation found a lognormal correlation coefficient of 0.93 (out of 1.00). These data showed more variance than that of the 1996 and 1997 drilling, with the variance between most sample-duplicate pairs being + 45 percent, indicating less analytical precision than in the later sample analyses. Comparison of the average grades found that the original analyses were 3 percent higher than the duplicates, a difference acceptable by normal engineering practice.

Overall, PAH found that the results from the check assaying are reasonable. PAH recommends the inclusion of standard samples to assess analytical precision. In addition, field duplicate samples and blank samples would allow for an assessment of sample preparation procedures.

It is PAHs opinion that the sample methods and analyses are representative of the deposits at the Guadalupe de Los Reyes Project, and that most of the Project data was generated by NCM by procedures that were carried out according to accepted industry standards using accepted practices.

PAH did not have the opportunity to verify sampling procedures and results by Meridian; duplicates and rejects were removed from NCMs storage to a different site. This data, however, has not been incorporated into the resource model databases.


14.0 DATA VERIFICATION

Neither Vista nor PAH have taken any independent samples from the exposures of the veins and quartz deposits as other Qualified Persons have previously sampled the mineralization as discussed in this report.

PAH examined the possibility of down hole contamination below underground workings and/or from high-grade intercepts using one of its standard statistical programs. This program operates by selecting all assay intervals that are above a certain cutoff value and then evaluating the assay intervals above and below the selected interval to determine if there is a statistical balance of grade values (tailing effect). The results indicated that for the El Zapote reverse circulation holes, there was a slight suggestion of down hole contamination locally. One questionable intercept for which a downward tailing effect was indicated (ZA-114 at 15.24 meters) should be further investigated. PAH notes that this test is not completely definitive, and it is possible that these intercepts may be attributable to natural deposit grade distribution. In general, PAH did not find evidence of s

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Technical Report for the Guadalupe de Los Reyes - Vista Gold Guadalupe de los Reyes... · Technical Report for the Guadalupe de Los Reyes Gold-Silver Project, State of Sinaloa, Western