Technical Report for the Guadalupe de Los Reyes Gold

Technical Report for the Guadalupe de Los Reyes Gold-Silver Project, State of Sinaloa, Western México

Prepared for Vista Gold Corporation July 17, 2003 9203.04

Technical Report for the Guadalupe de Los Reyes Gold-Silver Project, State of Sinaloa, Western Mexico

Prepared for Vista Gold Corporation

Denver

Jersey City

July 17, 2003 9203.04

Prepared by Pincock, Allen & Holt

Lima

Raúl Borrastero Leonel López, C.P.G. Mark G. Stevens, C.P.G. Santiago

Seattle

A Division of Hart Crowser

274 Union Boulevard, Suite 200 Lakewood, Colorado 80228-1835 Fax 303.987.8907 Tel 303.986.6950

CONTENTS 1.0

2.0

Page

EXECUTIVE SUMMARY

1.1

1.1 1.2 1.3 1.4 1.5 1.6

1.1 1.1 1.2 1.3 1.4 1.5

Location Ownership Geology and Mineralization Exploration and Project Data Geologic Resources Conclusions and Recommendations

INTRODUCTION AND TERMS OF REFERENCE

2.1

2.1 2.2

2.1 2.1 2.1 2.2 2.2 2.2

2.3 2.4 2.5

Terms of Reference Purpose of the Technical Report 2.2.1 Sources of Information Site Visit Terms and Definitions Units

3.0

DISCLAIMER

3.1

4.0

PROPERTY DESCRIPTION AND LOCATION

4.1

4.1 4.2 4.3 4.4 4.5 4.6 4.7

Property Description Location Project Ownership Guadalupe de Los Reyes Concessions Option Agreement Mineral Tenure Surface Land Ownership Environmental and Permitting

4.1 4.1 4.1 4.3 4.5 4.5 4.8

ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

5.1

5.1 5.2 5.3

5.1 5.1 5.1

5.0

Accessibility Climate and Physiography Local Resources and Infrastructure

6.0

HISTORY

6.1

7.0

GEOLOGICAL SETTING

7.1

Pincock, Allen & Holt 9203.04 July 17, 2003

Page i

CONTENTS (Continued)

7.1 7.2 7.3 7.4 7.5

Guadalupe de Los Reyes Project Regional Geologic Setting El Zapote Deposit Geology Guadalupe Mine Deposit Chiripa – San Miguel – Noche Buena Deposits Tahonitas Deposit

Page

7.1 7.3 7.5 7.5 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 16.2

16.1 16.2

17.0

Historical Metallurgical Test Work Recent Metallurgical Test Work

MINERAL RESOURCE ESTIMATES

17.1

17.1 17.2 17.3 17.4 17.5

17.1 17.1 17.4 17.4 17.6 17.8 17.8 17.8

17.6 17.7

Introduction Computerized Modeling Rock Models Grade Models Geologic Resources 17.5.1 Vista Classified Resources Geologic Reserves Additional Resource Potential


Page ii


Page

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 4-2

Vista Gold Mineral Concessions Currently Under Option Mineral Concessions of The Guadalupe de Los Reyes District

4.3 4.6

6-1

Summary of Projection Guadalupe de Los Reyes Mining District

6.1

9-1

General Deposit Data

9.2

11-1 11-2

Data Verification, Meridian Gold Drill Hole Location Guadalupe de Los Reyes Project – Drilling and Drill Samples Assayed.

11.5 11.9

12-1 12-2

RC Hole Cutting Samples and Geochemical Sampling RC Hole Cutting Samples for Metallurgical Testworks

12.1 12.2

16-1 16-2 16-3

Mineralized Material Sample Identification – Head Assays. Results of Cyanide Bottle Roll Tests Results of Column Leach Tests

16.2 16.3 16.4

17-1 17-2 17-3 17-4

Guadalupe de Los Reyes Project – Composite Statistics Mineral Deposits Search Interpolation Parameters Based on Variography(*) Block Model Statistics of El Zapote and Guadalupe Laija Deposits (*) Comparison of SRK & Minorex Krige and PAH NN Block Models

17.3 17.5 17.5 17.6


Page iii


Page

17-5 17-6

17.7 17.7

Vista Mineral Resources (Within Gaitán Concessions) @ 0.5 g/t Au Vista Mineral Resources (Within Gaitán Concessions) @ 1.0 g/t Au

FIGURES 4-1 4-2

General Location Map Guadalupe de Los Reyes Mining District Concessions Map

7-1 7-2 7-3 7-4 7-5 7-6 7-7

Guadalupe de Los Reyes Mining District Geological Setting El Zapote Deposit, Cross Section 5450 (Looking Northwest) Guadalupe Mine Underground Development Guadalupe Deposit Cross Section 4900 (Looking West) San Miguel Deposit Cross Section 5150 (Looking Northwest) Noche Buena Deposit Cross Section 4600 (Looking Northwest) Tahonitas Deposit Cross Section 4650 (Looking Northwest)

8-1

Illustration Of Epithermal Model

8.2

9-1

Deposits Covered by Vista Optioned Claims

9.3

11-1 11-2 11-3 11-4 11-5 11-6

Correlation Collar/Topography For The El Zapote Deposit Correlation Collar/Topography For The Chiripa – San Miguel Deposit Correlation Collar/Topography For The Guadalupe Laija Deposit El Zapote – Tahonitas – Chiripa Drill Hole Locations San Miguel – Noche Buena Drill Hole Locations Guadalupe Mine Drill Hole Locations

11.2 11.3 11.4 11.6 11.7 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 Indicated Resources Tonnage – Grade variability at different Cutoffs for the Tahonitas deposit Indicated Resources Tonnage – Grade variability at different Cutoffs for the Noche Buena deposit Indicated Resources Tonnage – Grade variability at different Cutoffs for the San Miguel - Chiripa deposit Indicated Resources Tonnage – Grade variability at different Cutoffs for the Guadalupe - Laija deposit

17-2 17-3 17-4 17-5


4.2 4.7 7.2 7.4 7.6 7.7 7.8 7.9 7.11

17.9 17.10 17.11 17.12 17.13

Page iv

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 43101, 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 Project’s 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 Project’s resource estimates.

1.1

Location

The Guadalupe de Los Reyes Gold-Silver Project is located in the State of Sinaloa, in western México, at approximately half of the distance between the cities of Mazatlán and Culiacán. The Project area is accessed by a 30-kilometer dirt road from Cosalá, a city of approximately 17,000 inhabitants. The city of Cosalá is connected to the cities of Mazatlán and Culiacán 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, Mazatlán and Culiacán.

1.2

Ownership

Vista has agreed with Mr. Enrique Gaitán 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. Gaitán 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. Gaitán of $20,000.00. Vista may terminate the option at any time. 2. At 4 months or before, Vista and Gaitán 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 Gaitán $500,000.00 or the equivalent in Vista shares. 4. At the second and subsequent anniversaries Vista would pay to Gaitán a yearly amount of $100,000.00 up to a total amount of $500,000.00. Pincock, Allen & Holt 9203.04 July 17, 2003

1.1

5. Vista will pay to Gaitán 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 Mazatlán. Most of the production was shipped from Mazatlán 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 MiguelNoche 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. Meridian’s drilling results did not meet the Company’s 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 México to the Basin and Range Province in the Pincock, Allen & Holt 9203.04 July 17, 2003

1.2

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, Bolaños, Guanajuato, La Ciénega, 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 project’s 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. Pincock, Allen & Holt 9203.04 July 17, 2003

1.3

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 Vista’s 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 4,209 404 459 515 751 9 6,347 (rounded)

Gold G/t 1.34 1.41 1.18 1.15 1.71 0.59 1.36 277,600

Silver G/t 9.3 48.4 23.6 70.8 53.2 19.1 23.0 4,697,800

INFERRED K Tonnes 107 290 1,144 173 2,106 20 3,840

El Zapote (*) Tahonitas Noche Buena San Miguel – Chiripa Guadalupe – Laija (*) Guadalupe – West TOTAL TOTAL CONTAINED Gold Ounces (*) Resource has been adjusted to reflect material removal from old u/g workings.


Gold g/t 1.78 1.54 1.13 1.80 2.59 0.66 2.01 247,850

Silver g/t 8.5 52.0 24.9 60.3 93.4 15.5 65.6 8,099,300

1.4

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 Project’s 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.


1.5

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 Raúl Borrastero, Senior Geologist Leonel López, C.P.G., Principal Geologist Other PAH personnel as required

2.2

Purpose of the Technical Report

Vista has agreed with Mr. Enrique Gaitán Enríquez 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. Gaitán’s 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 Pacífico, 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, PAH’s 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


2.1

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 Farías. 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 project’s current status, present infrastructure conditions and the exploration efforts carried out by NCM and Meridian. The site visit was performed by PAH’s representative Leonel López 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, Gaitán refers to Mr. Enrique Gaitán Enríquez, 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 Pacífico, 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-México.


2.2

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 user’s 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).


3.1

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. Gaitán’s 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 Gold’s control, that are controlled by the mineral rights held by Mr. Gaitán’s 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 project’s 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 Mazatlán. 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 Cosalá (17,269 inhabitants, INEGI 2000), in Sinaloa State. General geographic coordinates for the Guadalupe Los Reyes mining district are approximately: N-24º 16´ 42" and W-106º 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 Cosalá within the State of Sinaloa, México. These are presented in Table 4-1 and Figure 4-2.


4.1

TABLE 4-1 Vista Gold Corporation Guadalupe de Los Reyes Project Vista Gold Mineral Concessions Optioned from Gaitán Exploration Claims Name Area (ha) La Victoria 199.2896 Prolongación del Recuerdo (1) 91.5951 Prolongación del Recuerdo Dos 25.8927 316.7774 Exploitation Claims Name Area (ha) Arcelia Isabel (2) 60.3723 Dolores 219.8283 280.2006 Total Hectares 596.9780

Title Number 192499 194053 192500

Title Number 193499 180909 (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 Culiacán, the state capital city of Sinaloa, at the Mining Agency (Agencia de Minería), at the Delegación Regional de Minería in Durango city, and the Central Mining Registry in México City (Dirección 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 Gaitán Enríquez, 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. Gaitán 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. Gaitán an Option to Purchase Agreement upon a first purchase payment of $400,000.00. Vista will reimburse to Mr. Gaitán up to $15,000.00 due to concession holding costs for 2002 and half of 2003.


4.3

3.

At the first anniversary from the signature date of the Option to Purchase Agreement Vista would pay to Mr. Gaitán 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. Gaitán the amount of $100,000.00 up to $500,000.00.

5.

Vista would pay to Mr. Gaitán 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. Víctor Juvera who was contracted by Vista to investigate the current legal status of land registration. Please refer to Figure 4-2. In accordance with PAH’s 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 Project’s 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 González y Socios (Dr. Matthew D. Gray’s report) while in the concession’s map it appears as owned by Minera Tatema (Mr. Enrique Gaitán Enríquez).

(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 “Prolongación del Recuerdo” concesión 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 Pacífico, 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 Pacífico, 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 Culiacán apparently owns numerous concessions. These were contracted under a purchase agreement by Compañía Minera Mariposa, which sub-contracted them to NCM. It appears that these claims have been returned to the


4.4

original concessionaires; if that is the case, then negotiations with these residents of the city of Culiacán maybe undertaken, or take over the purchase agreement. (7)

Compañía 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 México are regulated by the Dirección General de Minas and by the Secretaría del Medio Ambiente from México 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 Project’s 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. Gaitán and by PAH’s 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 México, 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. Gaitán, and the Ejido Tasajera are still valid.


4.5

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

NOTES

La Victoria

210803

Minera Tatemas, S.A. de C.V.

Mr. Enrique Gaitán E. (1)

Prolong. Del Recuerdo

210497



Prolong. Del Recuerdo 2

209397



Arcelia Isabel

193499

Mr. Enrique Gaitán E.


Dolores

180909

Jaime Guinea G. Y Socios


10 de Mayo

208790


Jaime Guinea G. y Soc.(*)

Seis de Enero

Exp-9857

Jaime Guinea G. Y Socios

Jaime Guinea G. y Socios.

El Faisán

211471

Minera Sierra Pacífico, S.A. de C.V.

Northern Crown Mines (?)

Patricia

212775



San Manuel

188187



Santo Niño

211513



Tominil

205768



Tominil Fracción

205769



Guadalupe Norte I

210471

Desarrollos Mineros del Pacífico, SACV

Luismin (Wheaton River)

Los Reyes Dos

214131



Los Reyes Tres

214303



Los Reyes Cuatro

217757



Los Reyes Cinco

216632



Los Reyes Fracc. Norte

212757



Los Reyes Fracc. Sur

212758



Los Reyes Fracc. Oeste

210703



Martha I

200768

Cía.Minera Mariposa,S.A. de C.V.

Pan Atlantic Group

Nueva Esperanza

184912

José Zazueta Gaxiola.

Socios Culiacán.

San Miguel

185761

José Zazueta Gaxiola.

Socios Culiacán.

El Padre Santo

196148

Cruz López Arredondo y Socios.

Socios Culiacán.

Norma

177858

Cruz López Arredondo y Socios.

Socios Culiacán.

San Pablo

212752

Vigente

Socios Culiacán (*).

San Pedro

212753

Vigente

Socios Culiacán (*).

(1) Vista Gold Corp. Option. (*) It is of PAH understanding.


(?) Dropped or still held by NCM. Research by: Mr.Víctor Juvera (Perito Minero).

4.6

4.7

Environmental and Permitting

According to Mr. Gaitán 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 mine’s 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.


4.8

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 Mazatlán, and Culiacán of the State of Sinaloa, and then to Cosalá by a 55-kilometer, two-lane paved highway. From Cosalá to the project area is a 30kilometer dirt road. An airstrip for small aircraft is located near Cosalá, with public and private service to the cities of Mazatlán, Culiacán 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 26°C 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 Cosalá. 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 Cosalá 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 Cosalá through Guadalupe de Los Reyes is the only regional access to the mountains to the east in this part of the Country. Cosalá offers retail, banking, medical, educational, hospital, and communications to the rest of the Country; however, major facilities are located in the cities of Mazatlán and Culiacán.


5.1

6.0

HISTORY

The Guadalupe de Los Reyes mining district was discovered, according to local residents on December 12, 1772 (virgin of Guadalupe’s day) and claimed on January 6, 1773 (Wise men’s day, “día 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 Miguel–Chiripa–Noche Buena, and Mariposa–Zapote-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 Cosalá 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

Guadalupe Los Reyes 1772 – 1871 Unknown Guadalupe Los Reyes 1872 - 1938 874,658 Minera Tatemas 1935 - 1944 170,000 El Zapote Oct.88 – Feb.89 31,529 TOTAL 1,076,187 CONTAINED OZ. Rounded (*) Based on Minas de San Luis research of production records.


Average Grade Gold Unknown 8.80 12.00 5.80 9.22 319,000

Average Grade Silver Unknown 521 <50 <50 433 14,982,000

6.1

Operating companies in the district included Negociación Minera de Guadalupe de los Reyes, S.A.; Compañía La Chiripa y Anexas; Compañía Candelaria Canoas, S.A., and in recent times Mr. Enrique Gaitán Enríquez representing various companies as Compañía Minera Campanillas, S.A. de C.V., Minera Tatema, S.A. de C.V., and Minera Sierra Pacífico, 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.


6.2

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 PAH’s 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 NeoVolcanic Belt in central México 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-


7.1

Upper Volcanic Sequence RHYOLITE Mariposa Zone GRANODIORITE

Structures Hosting Gold-Silver Mineralization Lower Volcanic Sequence ANDESITE

Guadalupe Mine Zone San Miguel Chiripa Zone

DACITE DOME

PORPHYRY STOCK Las Primas Zone

Zapote Zone DACITE DOME

DACITE DOME

Noche Buena Zone DACITE DOME Upper Volcanic Sequence RHYOLITE Tahonitas

Fresnillo Zone

N

Upper Volcanic Sequence RHYOLITE

Zone

0

500

1000

Scale in Meters Prepared by

PINCOCK, ALLEN & HOLT

274 Union Boulevard, Suite 200 Lakewood, Colorado 80228 Phone (303) 986-6950 Project No.

9203.04

Prepared for

VISTA GOLD CORP. Project Name

Guadalupe de Los Reyes Project

Date of Issue

FIGURE 7-1

GEOLOGY MAP - GUADALUPE DE LOS REYES AREA

June/2003 Drawing Name

Fig7-1.cdr

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 Pincock, Allen & Holt 9203.04 July 17, 2003

7.3

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 district’s 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 50º-60º 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.


7.5

LAIJA WEST

Gold - Silver Mineralization

Prepared by



9203.04

Prior Recorded Production 247,500 Ounces Gold 14.7 Million Ounces Silver

Prepared for



Date of Issue

FIGURE 7-3

GUADALUPE MINE - UNDERGROUND DEVELOPMENT


Fig7-3.cdr

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 45º to 60º 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.


7.10

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.


8.1

Prepared by



9203.04

Prepared for



Date of Issue

FIGURE 8-1

EPITHERMAL MODEL


Fig8-1.cdr

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 yellowgreen 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 finegrained 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.


9.1

TABLE 9-1 Vista Gold Corporation Guadalupe de Los Reyes Project General Deposit Data Deposit Explored Extension Length: 1,000 meters. El Zapote 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. 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. Length: 1,400 meters. San Miguel 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. 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. 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.


General Characteristics Structure: El Zapote–Tahonitas–Mariposa. Strike: NW . Dip: 50º to W. Contacts: Sharp footwall contact and stockwork to the hanging wall. Structure: Southern extension of the El Zapote–Tahonitas–Mariposa. Strike: S 30º E. Dip: 45º to 60º to the SW. Contacts: Sharp footwall, some veining to the hanging wall. Structure: San Miguel – Noche Buena– Chiripa. Between the El Zapote and Guadalupe structures. Strike: S70ºE. Dip: 70º to the SW. Contacts: Sharp both walls. Structure: San Miguel-Noche BuenaChiripa, in SE extension. Strike: S30ºE. Dip: 50º to 60º to the SW. Contacts: Sharp footwall and stockwork to the hanging wall. Structure: Guadalupe mine. Strike: S 80º-70ºE. Dip: 65º to 90º to SW. Contacts: Sharp in veins within breccia zone, extensions to the NW of the old workings and to the SE, Laija.

9.2

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 Gaitán 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. Gaitán, approximately 93 kilograms of gold from a small cyanide vat leach facility. Minera Sierra Pacífico, 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


10.1

Mr. Enrique Gaitán, Minas de San Luis, Minera Mariposa, and a group of concessionaires from the city of Culiacán. In January 2003 Vista Gold Corp. entered an agreement to acquire 100 percent of the mineral rights held by Mr. Gaitán, 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.


10.2

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 Meridian’s 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.


11.1

25

20

Meridian Holes

Series1 15

10

196

191

186

176

171

166

161

156

151

146

141

136

131

126

121

116

111

106

101

96

91

86

81

76

71

66

61

56

51

46

41

36

31

26

21

16

11

6

181

Topo +\-

0 1

Meters

5

-5

-10

-15

-20

# Drillholes Prepared by



9203.04

Prepared for



FIGURE 11-1

CORRELATION COLLAR/TOPOGRAPHY EL ZAPOTE DEPOSIT

Date of Issue


Fig11-1.cdr

15

10 Series1 5

49

47

45

43

41

39

37

35

33

31

29

27

25

23

21

19

17

15

13

11

9

7

5

3

1

0

Meters

-5

Topo +\-

-10

-15

-20

-25

-30

-35

Meridian Holes

-40




9203.04

Prepared for



FIGURE 11-2

CORRELATION COLLAR/TOPOGRAPHY CHIRIPA - SAN MIGUEL DEPOSITS

Date of Issue


Fig11-2.cdr

20

15

Meters

10

Topo +\-

5

63

61

59

57

55

53

51

49

47

45

43

41

39

37

35

33

31

29

27

25

23

21

19

17

15

13

11

9

7

5

3

1

0

-5

-10




9203.04

Prepared for



FIGURE 11-3

CORRELATION COLLAR/TOPOGRAPHY GUADALUPE LAIJA DEPOSIT

Date of Issue


Fig11-3.cdr

TABLE 11-1 Vista Gold Corporation Data Verification Meridian Drill Hole Locations AREA LOCATION

EAST

MERIDIAN NORTH Elev. M

GPS READING PAH EAST NORTH Elev. M

% DIFFERENCE Eastings Northings Elevations

San Miguel GS-01

345276

2685076

690

345274

2685069

663

0.00

0.00

-3.91

GS-02 GS-03 GS-04

345276 345215 345218

2685073 2685024 2685032

690 715 715

345274 345212 345212

2685069 2685031 2685031

663 681 681

0.00 0.00 0.00

0.00 0.00 0.00

-3.91 -4.76 -4.76

GS-05 GS-06

345268 345274

2684940 2684942

730 730

345266 345266

2684943 2684943

694 694

0.00 0.00

0.00 0.00

-4.93 -4.93

GC-01 GC-02

344106 344104

2685280 2685280

757 757

344107 344107

2685277 2685277

739 739

0.00 0.00

0.00 0.00

-2.38 -2.38

GC-03 GC-04

344396 344393

2685304 2685309

723 723

344395 344395

2685302 2685302

704 704

0.00 0.00

0.00 0.00

-2.63 -2.63

GC-05 GC-09

344393 344503

2685306 2685315

723 738

344395 344508

2685302 2685306

704 703

0.00 0.00

0.00 0.00

-2.63 -4.74

Chiripa

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.


11.5

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 Meters Drilled Drill Samples Total

197

78

33

25

33

8

1

375

15,728.14

10,547.00

3,674.35

2,592.55

2,257.98

1,139.97

166.12

36,106.11

10,234

6,899

2,361

1,671

1,449

748

106

23,468

Meridian Gold Inc. 5

9

6

0

0

3

0

23

829.3

829.2

698.2

0

0

375.0

0

2,731.7

378

9

39

0

0

6

38

470

RC No. Drill Holes Meters Drilled Drill Samples Total (*)

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.


11.9

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 1.52meter 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 Geochemical Soil Rock(*) El Zapote 151 105 Guadalupe 1,134 422 San Miguel 513 339 Noche Buena 314 111 Tahonitas 512 80 El Orito 564 64 651 212 Mariposa 621 115 Other Zones TOTAL 4,460 1,448

No. RC (1) Drill Samples 10,612 6,908 2,400 1,671 1,449 754 144 0 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 (Gaitán Footwall Sample) consists of strongly silicified/quartz vein material near the footwall of the structural zone in a small excavation known as the Gaitán Cut; the initial sample analysis ran 2.42 g/t Au and 34.3 g/t Ag. Sample D (Gaitán Stringer Sample) consists of strongly silicified/quartz vein material in the gradational hanging wall of the structural zone in the Gaitán 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


12.1

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 (ZA088 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 ZPF – 01 ZA-077, 159. 36.28 ZPF – 02 ZA-073, 078. 65.54 ZPF – 03 ZA-168, 176. 41.15 ZPF – 04 ZA-087, 147, 150. 27.44 ZPF – 05 ZA-092, 113. 13.72 ZPF – 06 ZA-102, 108, 109. 19.81 ZPF – 07 ZA-088, 095, 096. 32.00 ZPF – 08 ZA-089, 123. 20.89 (*) Head samples assayed by fire fusion procedures. McClelland Labs.


Gold g/t 1.85 1.53 1.25 1.35 0.75 1.05 1.06 1.82

Silver g/t 11.40 8.90 10.70 12.30 13.20 20.80 9.40 20.10

12.2

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, México 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, México. 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, BondarClegg 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.


13.1

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 ZA016 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. PAH’s 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 PAH’s 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 NCM’s storage to a different site. This data, however, has not been incorporated into the resource model databases.


13.2

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 systematic down hole contamination that would significantly affect the resource modeling results. PAH carried out a review of the check assay program for the Prefeasibility Report, including correlation analysis of results for duplicate checks, and the conclusion was that the results from check assaying were reasonable. NCM personnel applied the same procedure to all sampling and data registration of all the investigated mineralized zones within the Project area. PAH believes that an adequate amount of checking has been conducted and that the results are representative of the mineralization in the deposit. Furthermore, PAH recommended to add field duplicate samples and blank samples to also check sample preparation procedures. No evidence of methodology or procedures for sampling drill holes by Meridian was provided to PAH to verify assay and intercept results. This data, however, has not been incorporated into the resource model databases.


14.1

15.0

ADJACENT PROPERTIES

The Guadalupe de Los Reyes Project includes eight target areas which have been identified by NCM and other operators along four major structural zones. The Guadalupe Mine has been the most developed by underground methods, El Zapote the most explored by modern methods, Tahonitas being the southern extension of the former, San Miguel located along an intermediate structure, and Noche Buena as the southern extension of San Miguel. Most of the land that encloses these deposits belongs to the concessions under purchase agreement by Vista, and the rest of the area of the deposits is covered by claims owned by Luismin, a Group of Associates from the city of Culiacán, and Minera Mariposa. Mariposa, Chiripa, and part of San Miguel deposits are not contained by the mining concessions under the present purchase negotiations by Vista. Please refer to Figure 4-2 for a general view of the Guadalupe Los Reyes Mining District concessions. The Guadalupe de Los Reyes Project is located in an isolated area within the northwest trending Sierra Madre Occidental. The nearest operating mines to this district are those within the Cosalá Mining District, such as La Reyna and La Estrella, approximately 30 kilometers to the northwest. About 60 kilometers to the east of the Guadalupe de Los Reyes Mining District are the similar epithermal type gold-silver deposits of the San Dimas and Tayoltita Mining District operated by Luismin (Wheaton River).


15.1

16.0

METALLURGICAL TESTING

16.1

Historical Metallurgical Test Work

According to petrographic studies the gold and silver minerals of the Guadalupe de Los Reyes Project occur as grains of native gold or electrum that typically range in size from 5 to 30 microns, with occasional coarser grains of up to 60 by 230 microns (0.23 mm). Approximately 50 percent of the grains are found liberated, while the rest are locked in quartz or occasionally intergrown with inclusions of Fe oxides. No other significant elements occur with the gold and silver that may interfere with the metallurgical recovery. Cyanidation methods are effective, provided that the grinding of the rock allows for the mineral grains to be reached by contact with the solvent solutions. The Guadalupe de Los Reyes Mining District has recorded production of approximately 320,000 ounces of gold and 15.0 million ounces of silver since 1872 (Minas de San Luis, S.A. de C.V.) in addition to an unknown amount from the District’s discovery in 1772. The majority of the production was processed by the methods of amalgamation and flotation in the Dolores plant, from 1872 to June 21, 1937 with installed capacity of 120 tpd. In 1935, the El Zapote plant initiated operations with a capacity of 40 tpd by a combined method of amalgamation and flotation. The plant operated until November of 1944 when the companies Minas Tatemas and Zapote closed both the mine and plant. In 1939, the Chiripa mine initiated processing the ore at the new Crosolia cyanidation plant with 100-tpd capacity. The plant operated until 1944 when all mining activities in the area were shutdown due to political unrest. The gold and silver recoveries at the Crosolia plant were reported at over 90 percent. Finally during the period of October 1988 to 1989, Compañía Minera Campanillas (Mr. Enrique Gaitán Enríquez) mined and processed 31,529 tonnes of mineral from the El Zapote deposit by vat leaching with cyanide extraction. The ore grade was reported as containing 5.8 g/t Au and less than 50 g/t Ag. Mr. Gaitán indicated a recovery of 93 kilograms of gold or approximately 51 percent of the contained gold. In October 1988, the Servicios Industriales Peñoles, S.A. de C.V. (Peñoles), Centro de Investigaciones Técnicas reported metallurgical test work for El Zapote samples submitted by Mr. Gaitán indicating recoveries for gold and silver by bottle roll tests of 96.70 and 49.39 percent respectively, at a size 67.04 percent passing minus 0.075 mm (-200 mesh). Column tests were carried out in several granolumetric compositions, and the best results (90.48 percent recovery for the gold and 44.51 percent for the silver) were obtained at a size of minus 0.50 mm (-35 mesh) with agglomeration. A separate sample submitted for vat leaching test reported recoveries of 55.06 percent for the gold, and 26.76 percent for the silver at a mineral size of minus 9.53 mm (3/8”). These tests indicate that recoveries are higher at finer grinding. In February 1990, a flotation test on the El Zapote mineral was also carried out by Peñoles resulting in recoveries of 84.15 and 40.43 percent of gold and silver, respectively, at a size of 81.11 percent minus 0.075 mm (-200 mesh).


16.1

16.2

Recent Metallurgical Test Work

In January 1995, Kappes, Cassiday & Associates reported results of metallurgical test work performed in samples submitted by NCM from the El Zapote deposit. These consisted of four drill cutting samples at minus 2.36 mm (-3/32”) size for bottle roll testing resulting in gold recoveries of 63.2 to 70.6 percent for a three day leach time (silver was not assayed). During the 1997 Prefeasibility effort, Tecnoco had more comprehensive metallurgical bottle roll tests developed by McClelland Laboratories de México, S.A. de C.V. on three bulk samples and eight drill cutting samples, composited from 461 separate RC samples from the El Zapote deposit. In PAH’s opinion these samples represent fairly well distributed sections of the El Zapote deposit. The samples tested are summarized in Table 16-1. TABLE 16-1 Vista Gold Corporation. Guadalupe de Los Reyes Project - Zapote Deposit Mineralized Material Sample Identification – Head Assays (1) Sample No. and Location

Head Assay g/tonne Au

Ag

Zapote Saddle Bulk Sample, El Zapote deposit (Sample A). (2)

3.31

16.8

Gaitan Footwall Bulk Sample, El Zapote deposit (Sample C). (2)

2.80

18.1

Gaitan Stringer Bulk Sample, El Zapote deposit (Sample D). (2)

1.73

27.6

Composite ZPF-01 Reverse Circulation Drill Samples, ZA-77, 159.

1.85

11.4


1.53

8.9


1.25

10.7

Composite ZPF-04 Reverse Circulation Drill Samples, ZA-87, 147, 150

1.35

12.3


0.75

13.2

Composite ZPF-06 Reverse Circulation Drill Samples, ZA-102,108,109

1.05

20.8

Composite ZPF-07 Reverse Circulation Drill Samples, ZA-88, 95, 96.

1.06

9.4

Composite ZPF-08 Reverse Circulation Drill Samples, ZA-89, 123. (1) Head samples assayed by fire assay fusion procedures. (2) Average value for bulk samples from triplicate fire assay.

1.82

20.1

The series of tests included crushing the bulk samples material to different sizes, while the drill cuttings were processed at the size received with no further crushing. The results of the bottle roll Pincock, Allen & Holt 9203.04 July 17, 2003

16.2

cyanide leach tests are summarized in Table 16-2. The average gold recovery at 70 percent minus 2.00 mm (-10 mesh) on the bottle roll tests of the eight composite drill cuttings samples is 58 percent. The average gold recovery at 70 percent minus 2.00 mm (-10 mesh) on the bottle roll tests of the feed to the three column leach tests (bulk samples) is 68 percent, while the average recovery in the column leach tests at minus 6.35 mm (-1/4”) is 86 percent, showing that the longer leach time column leach tests, which closely approximate heap leach conditions, give a recovery that is 18 percent higher than the bottle roll tests on the same material. The indicated heap leach recovery, applying this difference to the bottle roll tests on the drill cuttings, is 76 percent. TABLE 16-2 Vista Gold Corporation Guadalupe Los Reyes Project - Zapote Deposit Results of Cyanide Bottle Roll Tests (*)

Grind -12.70 mm

G/tonne Calc. Head Tails Au Ag Au Ag 3.25 15.1 2.03 16.9

% Recovery Au Ag 37.5 13.8

-9.53 mm -6.35 mm -10.0 Mesh

3.34 3.32 3.42

16.8 16.3 13.5

1.98 1.74 1.38

9.4 15.4 10.6

40.7 47.6 59.6

23.6 16.8 27.4

0.14 0.23 0.15

1.5 1.4 1.5

-12.70 mm

2.78

19.6

1.17

13.2

57.5

12.6

0.07

1.2

-9.53 mm -6.35 mm -10.0 Mesh

2.82 2.95 2.82

12.3 18.5 14.6

1.14 1.06 0.76

14.6 13.4 10.1

59.6 64.1 73.0

13.1 17.8 25.2

0.16 0.16 0.16

1.2 1.2 1.5

-12.70 mm

1.75

31.5

0.74

24.5

57.5

22.2

0.06

1.6

-9.53 mm -6.35 mm -10.0 Mesh

1.70 1.77 1.83

24.8 29.3 26.3

0.64 0.62 0.50

19.0 20.7 16.9

62.4 65.0 72.7

23.4 29.4 35.7

0.14 0.22 0.09

1.5 1.5 1.8

Composite ZPF-01 -10.0 Mesh 2.05 17.4 0.81 Composite ZPF-02 -10.0 Mesh 2.04 12.2 0.73 Composite ZPF-03 -10.0 Mesh 1.65 13.3 0.69 Composite ZPF-04 -10.0 Mesh 1.89 12.1 0.95 Composite ZPF-05 -10.0 Mesh 1.06 14.4 0.45 Composite ZPF-06 -10.0 Mesh 1.57 25.1 0.62 Composite ZPF-07 -10.0 Mesh 1.28 8.20 0.69 Composite ZPF-08 -10.0 Mesh 2.07 23.0 0.51 (*) Head Assays from Bottle Roll Tests. McClelland Lab. Report.

13.0 8.9 10.4 11.1 11.5 19.2 11.7 16.7

60.5 64.2 58.2 47.5 57.5 60.5 43.0 75.4

25.3 27.0 21.8 22.9 20.1 23.5 12.0 27.4

0.23 0.29 0.30 0.40 0.15 0.22 0.16 0.37

2.1 2.7 2.6 2.2 2.0 1.9 1.0 1.4

Sample Zapote Saddle Bulk Sample (Sample A)

Gaitán Footwall Bulk Sample (Sample C)

Gaitán Stringer Bulk Sample (Sample D)

Kg/Tonne NaCN Lime 0.14 1.3

The column leach tests are presented in Table 16-3. Tecnoco complemented analysis of these results with the application of the METSIM software. The development of a METSIM model for column leaching includes input of kinetic leaching information from test work conducted on the


16.3

various mineralized material types. Extraction curves can be developed from column leach data that accurately depict the rate and level of extraction for a particular set of leaching conditions and material types. Non-steady state simulation within METSIM utilizes first order rate equations. In order to fit extraction versus time curves, a technique has been developed which uses two first order equations to fit the measured data. This is based on the hypothesis that some of the material reacts at a rapid rate, some at a slower rate, and some not at all.

TABLE 16-3 Vista Gold Corporation Guadalupe Los Reyes Project - Zapote Deposit Results of Column Leach Tests Sample

100% Leach minus/m time, m Days

Assay Head

% Recovery (1)

Kg/tonne

Au

Ag

Au

Ag

NaCN

Lime

P1 Zapote Saddle

12.70

67

3.31

16.8

64.56

14.28

1.45

1.0

P2 Zapote Saddle

9.53

53

3.31

16.8

62.81

15.15

1.23

1.2

P3 Zapote Saddle

6.35

53

3.31

16.8

71.61

17.50

1.17

1.1

P4 Gaitán Footwall

12.70

67

2.80

18.1

85.76

17.14

1.25

1.0

P5 Gaitán Footwall

9.53

67

2.80

18.1

83.88

18.64

1.37

0.9

P6 Gaitán Footwall (a)

6.35

47

2.80

18.1

91.08

19.50

1.34

1.0

P7 Gaitán Footwall (b)

6.35

67

2.80

18.1

83.93

19.84

1.34

1.0

P8 Gaitán Stringer

12.70

60

1.73

27.6

83.74

26.88

1.24

1.3

P9 Gaitán Stringer

9.53

60

1.73

27.6

81.52

29.86

1.19

1.2

P10 Gaitán Stringer

6.35

53

1.73

27.6

94.31

35.01

1.31

1.2

(a) Leach test to provide material for environmental testing (b) Leach test to provide metallurgical data (1) Percent recovery for gold based on calculated heads and extrapolation of leach curves to 180 days using leach equations from the METSIM heap leach computer model. Percent recovery for silver based on silver extracted vs. assay heads.

The results of these percolation leach tests and METSIM computer modeling to extrapolate results to 180 days of leaching show that crushing to minus 6.35 mm (-1/4”), 9.53 mm (-3/8”), or 12.70 mm (-1/2”) produced an average of 85 percent gold extraction, after 47 to 67 days leach time.


16.4

PAH recommends that further test work be conducted in order to better define the process variables. PAH further recommends that additional test work be conducted on samples taken at depth from the El Zapote property in order to establish the following: Precious metal recoveries on representative core samples The evaluation of surfactants to improve recovery Reagent consumptions Effects of contaminants on plant operation.


16.5

17.0

MINERAL RESOURCE ESTIMATES

17.1

Introduction

PAH completed a review of the database and the computer block model for the El Zapote Zone as part of its Prefeasibility Study in 1997-1998. The El Zapote zone was modeled by SRK and subsequently checked by PAH as part of the Prefeasibility Study. All other zones were modeled by Minorex during late 1997 using similar criteria as those established by SRK for the El Zapote deposit, but were not part of the Prefeasibility. No further drilling has been performed by NCM since 1997. Meridian carried out a confirmatory drilling program that included 23 reverse circulation holes distributed in various mineralized zones of the Project during 2002. These holes were drilled to test projections of geological and mineral trends, and in PAH’s opinion if the results of these later holes were included in the geologic models used for the resource estimate developed herein, no significant changes in tonnage or grade would result.

17.2

Computerized Modeling

The Project database was maintained and updated by NCM personnel. The El Zapote computer model was created by SRK, and the models for Guadalupe Laija and West, Chiripa - San Miguel, Tahonitas, and Noche Buena were created by Minorex using similar parameters. A block size of 5by 5-meters in plan with a 5-meter bench height was chosen by SRK as a size that allowed for the delineation of geologic features and still provided a reasonable mining unit. Due to the structural orientation of the deposit, SRK decided that a better model representation was achieved by rotating the model 19.5 degrees, so that the model blocks parallel the strike and dip of the mineralized zone. Minorex rotated the other models 69.4 degrees (Guadalupe Laija and San Miguel Chiripa), 79.4 degrees (Guadalupe West), and 29.4 degrees (Noche Buena and Tahonitas). The computer models for these areas were also based on a block size of 5 by 5 by 5 meters and they were created in Gemcom software following similar parameters as those used by SRK for the El Zapote deposit. PAH had to restore the Guadalupe Laija deposit model, based on previous Minorexestablished parameters, due to defective electronic files. The results thus obtained are similar to those reported by Minorex, except for the grade capping values, which, in PAH’s opinion, should have been 20.00 g/t for gold affecting three composites, and 500 g/t for silver that affected five composites. PAH believes that these modeling setup parameters are reasonable for this project. The drill hole database for the mineralized zones within the Guadalupe de Los Reyes Project consists entirely of reverse circulation holes drilled by NCM. The Meridian holes were not used. For the El Zapote deposit it included a total of 201 drill holes containing 10,215 sample intervals. Drill hole sample intervals are almost entirely at 1.52-meter intervals (equivalent to 5-foot samples). Sample intervals include data for geology, gold, silver and density. The database for the Guadalupe Mine zone consisted of 78 holes and 1,073 sample intervals for gold and 1,160 for silver, including 63 holes for the Guadalupe Laija deposit with 917 gold sample intervals and 1004 for silver. The San Miguel – Chiripa zones were modeled with 33 holes containing 246 and 289 sample intervals Pincock, Allen & Holt 9203.04 July 17, 2003

17.1

for gold and silver. The Noche Buena zone model was based on 25 holes and 208 sample intervals. The Tahonitas zone model was developed from 33 holes and 115 sample intervals. The number of samples that were used in composites for the modeling and resource estimates represent less than about 30 percent of the total number of assayed samples. NCM sampled and assayed the whole length of all the drill holes. Samples with less than detectable gold and silver values are variably recorded in the NCM database. Earlier drill hole samples have a blank value assigned, while later drill holes show the analytical threshold (for gold: 0.03 or 0.01 g/t; for silver 0.33 g/t). PAH believes that all sample intervals in which the grade analysis was below the analytical threshold value should be entered in the database as a grade of 0.00 g/t Au. This is a subtle but important distinction to ensure that these assayed samples are not treated as missing samples during subsequent grade modeling. SRK, for their work, has appropriately adjusted the gold and silver values to 0.00 g/t Au or 0.00 g/t Ag before they created composites in their mine-modeling database. In holes in which no silver sampling was conducted, SRK did assign missing values, as was appropriate. Data entry was conducted by NCM personnel. PAH assessed the integrity of the gold reporting in the database by comparing the gold values on the original laboratory assay sheets to the assay values in the database for drill holes in the Zapote zone. Approximately 10 percent of the gold and 5 percent of the silver values were checked from assay sheets pulled on a random basis. Only one gold data entry error (ZA-051, 15.24 - 16.76 meters) and no silver entry errors were found, indicating a high quality database. SRK composited the original drill hole sample values into 3-meter intervals to normalize the different sampling intervals found in the database, while Minorex kept composites at 1.52-meter or direct assay intervals. During compositing, rock codes were backmarked to the composites from the rock model and compositing was conducted only for those composites marked with a mineral envelope code. Compositing was not conducted across areas flagged as underground workings. Partial length composites that were generated at the edge of the mineralized envelope or at the edge of the workings were not used for subsequent modeling by SRK if they had a length of less than 1 meter. PAH recommends limiting partial length composites to no less than one half of a full length composite (or 1.5 meters in this case) to maintain distance normalized data. PAH found that 329 composites out of 2,905 total composites had lengths between 1 meter and 3 meters. PAH evaluated these composites to check for the occurrence of short length, high grade samples that could affect the subsequent modeling. The results indicated that the partial length composites generally were not a problem, but notes that two short length, high grade composites occur that have a localized influence in the grade models (ZA-102 at 35.05 meters: 1.91 meters at 69.85 g/t Au and ZA-158 at 36.00 meters: 1.87 meters at 15.01 g/t Au). Both composites occur in locations immediately above underground void areas. Statistical evaluation of the El Zapote 3-meter composite data and 1.50-meter composites of the other areas, for the mineral envelope are summarized in Table 17-1. Composite statistics for both gold and silver indicate lognormal distributions with a few high-grade outliers. The coefficient of Pincock, Allen & Holt 9203.04 July 17, 2003

17.2

variation is relatively high reflecting composite grade variability, as is common in structural zone gold deposits. For lower grade gold values, the data shows relicts of analytical threshold values (at 0.03 and 0.01 g/t Au). SRK capped the high-grade gold outliers at 15 g/t Au, affecting 5 composites, and the silver outliers at 45 g/t Ag, affecting 8 composites. Minorex capped the high grade gold and silver outliers as indicated in Table 17-1, with no composites affected; however, PAH elected to institute capping values for the Guadalupe Laija model with capping values of 20 grams for gold (affecting 3 composites) and 500 grams for the silver (affecting 5 composites). Based on the review of the composite statistical information for the other models, PAH concurs with the SRK capping levels and suggests those indicated in Table 17-1, since Minorex did not apply capping cuts in the models. TABLE 17-1 Vista Gold Corporation Guadalupe de Los Reyes Project Composite Statistics (Mineralized Envelope) DEPOSIT Type Number Mean Comp. (g/t)

Maximum (g/t)

Minimum (g/t)

Std. Dev. (g/t)

Grade (g/t) CAP-Var (*) Gold 2,905 0.64 69.90 0.00 2.01 15.00 El Zapote Silver 2,124 5.70 97.00 0.00 6.70 45.0 Guadalupe Laija Gold 917 1.48 28.59 0.04 2.89 20.00 Silver 1,004 44.1 707.0 0.80 80.3 500 Guadalupe West Gold 156 1.30 29.82 0.05 2.97 7.00 Silver 156 22.2 181.8 1.00 17.6 150.0 San Miguel – Gold 246 1.34 80.22 0.04 5.11 6.00 Chiripa Silver 289 21.0 484.1 0.80 20.8 120.0 Tahonitas Gold 115 1.08 13.51 0.00 1.89 6.00 Silver 115 40.2 659.8 0.90 78.0 185.0 Noche Buena Gold 208 0.97 10.91 0.06 1.31 5.00 Silver 208 21.3 144.3 1.00 22.6 73.0 Note: Silver statistics are based on acid digestion analysis that gives a partial (soluble) silver grade value. (*) As suggested and modified by PAH.

A suite of variograms were constructed by SRK and Minorex to evaluate the lateral continuity and variability of the composites within the mineral envelope. The El Zapote composites for the analysis were divided geographically into two zones; the north zone (northwest) strikes at a 340-degree azimuth, and the south (southeast) zone strikes at a 305-degree azimuth. Both zones have a structural dip of 50 degrees to the southwest. The variography for the two zones showed similar geostatistical results. Gold variography showed ranges of 40 meters in the dipping structural plane, with the nugget accounting for approximately 40 percent of the total composite variance, suggesting moderate local variability. Silver variography showed similar ranges, with the nugget accounting for approximately 55 percent of the total composite variance, suggesting greater local variability than the gold composites. Guadalupe Laija deposit showed a longer-range variography for the strike, similar projections across the mineralized structure, and shorter range for downdip extension than those estimated for the El Zapote deposit. Table 17-2 shows the kriging parameters


17.3

determined by Minorex for the other mineral deposits within the Project area. PAH ran some check variograms on the composite data and concurs with SRK and Minorex results.

17.3

Rock Models

NCM personnel interpreted the geology of the deposit on cross sections oriented northeastsouthwest and spaced at 25-meter increments for the El Zapote zone and at 50-meter or longer intervals for the other zones. On these sections, the boundaries of the mineralized zone or mineral envelope were delineated. The mineralized envelopes were digitized and wireframed to create three-dimensional solid bodies. The down-dip extension of the mineral envelope was constrained by the 450-meter elevation at El Zapote, at 580-meter elevation for the Guadalupe Mine zone, and at 590 meter elevation for Noche Buena. These files were used by SRK and Minorex to create a three dimensional block representation of the mineral envelope. For blocks on the edge of the mineral envelope, a block percentage was recorded. The rock model was used to control the previously discussed compositing and for control during the subsequent grade modeling. Based on review of the model in digital and hard copy forms, PAH believes that the mineralized zone is reasonably represented. Previously mined underground drifts and stopes were delineated by NCM personnel to ensure that the current resource does not include areas that have previously been mined. Drift and stope boundaries were digitized in plan from incomplete and sketchy historical information and were wireframed to create three-dimensional solid bodies. Based on the narrower size of the underground voids intercepted during the recent in-fill drilling program, NCM has reduced the size of the underground mine shapes from what was originally digitized from historical information. These solid bodies were incorporated into the block model as a block percentage rather than as a whole block feature because the narrow dipping stopes are not reflected accurately by the current block size (5- by 5- by 5-meters). For the El Zapote model, it is estimated that 166,000 tonnes of stope and drift material has been removed from the mineral envelope area, which compares closely with the 170,000 tonnes indicated by historical records. For the Guadalupe – Laija model PAH did not have the block percentage model available and hence, subtracted the old workings from the estimate based on wireframe (solids) models, available from Minorex, that intersected the mineralized zone. A total of 668,000 tonnes of material were estimated to have been mined down to an elevation of 580 meters, which is a small tonnage compared to the total resource estimate and historical production. No significant volumes were mined out from the other zones. These figures approximate historical production records from the areas examined. Attempts to further delineate the underground workings should continue; however, PAH believes that NCM has reasonably accounted for the workings based on the current data.

17.4

Grade Models

Gold and silver grade models were created by SRK for the Zapote deposit, and by Minorex for the other mineralized zones within the Project area using ordinary kriging estimation methods. Individual blocks were assigned grade from capped composites using a search ellipsoid oriented Pincock, Allen & Holt 9203.04 July 17, 2003

17.4

along the plane of the dipping structural zone of the deposit. Kriging was conducted in two passes for gold, three passes for silver, in order to fill in blocks within the mineral envelope that occur at greater distance from composites. Search ellipsoid orientation parameters are summarized in Table 17-2. A very limited volume coded as dump material (from previous small scale mining operations) was not assigned a grade in the model, as is appropriate. TABLE 17-2 Vista Gold Corporation Guadalupe de Los Reyes Project Mineral Deposits Search Interpolation Parameters Based on Variography (*) Deposit Kriging No. Maximum Ellipsoid Radius (m) Pass Composites Comp./Holes Strike Dip Perp. El Zapote Gold 1 3 2 40 40 15 2 3 2 60 60 22.5 1 3 2 40 40 20 2 3 2 60 60 30 3 3 2 80 80 40 Guadalupe Laija (1) 1 3 2 75 10 15 Gold 2 2 2 150 20 30 Guadalupe West (1) 1 3 2 110 45 15 Gold 2 2 2 165 70 25 Noche Buena (1) 1 3 2 170 30 50 Gold 2 2 2 250 60 100 Chiripa – San Miguel 1 3 2 50 50 50 (1) Gold 2 2 2 100 100 100 Tahonitas (1) 1 3 2 110 30 30 Gold 2 2 2 220 60 60 (*) Determined by SRK (El Zapote) and Minorex. (1) No data on silver was available from Minorex.

Silver

Statistical evaluation of the resulting grade models for the El Zapote and Guadalupe Laija deposits found that the kriging tended to smooth grade within the grade model, as is typical with this approach. Grade model statistics are summarized in Table 17-3. TABLE 17-3 Vista Gold Corporation – Guadalupe de Los Reyes Project Block Model Statistics (Mineralized Envelope) of El Zapote and Guadalupe Laija Deposits (*) Type No. Blocks Mean (g/t) Std.Dev.g/t Minimum El Zapote Gold 60,362 0.55 0.75 0.002 Silver 64,548 5.60 4.80 0.40 Guad. Laija Gold 23,998 1.54 2.12 0.04 Silver 24,772 53.1 86.5 0.80 (*) By PAH. No capping was applied by Minorex.

Maximum

Coeff.Var.

7.27 45.0

1.36 0.90

16.2 639

1.38 1.63

PAH tested the El Zapote gold models for local estimation integrity by comparing individual composite values against the block value in which the composite is located. Overall, the Pincock, Allen & Holt 9203.04 July 17, 2003

17.5

comparison is reasonable and shows smoothing trends typical of kriged models, with block values to the right of the ideal 1:1 line being lower than the contained composites, while to the left the block values are higher than the contained composites. Average grade of the composites and blocks in the pairs compares very closely and suggests that, on a local basis, there is an overall balance in the smoothing of high and low grades in the model. PAH further tested the global integrity of the Zapote and the Guadalupe Laija gold models for grade bias by creating a nearest neighbor model (computer polygonal model unconstrained by geology) and then comparing the block results with the El Zapote SRK kriged model and the Guadalupe Laija Minorex kriged model. A nearest neighbor model provides a geometrically declustered average grade, at a zero cutoff, thereby assuring against undue weighting by individual composites. As a result, PAH would expect that the average krige grade would be no more than the average nearest neighbor grade. The results indicated that this is not the case for the kriged gold models, suggesting that on a global basis there is a slight tendency for the kriged model to disproportionately smear higher composite gold grades laterally in the mineral envelope. Attempts to reduce this smearing should be evaluated further, but the effect does not appear to be severe enough to be a major issue for this study. Please refer to Table 17-4. TABLE 17–4 Vista Gold Corporation – Guadalupe de Los Reyes Project Comparison of SRK & Minorex Krige and PAH NN Block Models (Mineralized Envelope) Model – Deposit No. Of Total Grade Grade of Indicated Blocks (g/t Au) Blocks (g/t Au) El Zapote SRK – Kriged 60,362 0.55 0.62 PAH NN 60,362 0.52 0.61 Guadalupe Laija Minorex Kriged 23,998 1.54 1.40 PAH NN 24,673 1.52 1.24

17.5

Grade of Inferred Blocks (g/t Au) 0.36 0.25 1.60 1.61

Geologic Resources

SRK and Minorex=s geologic resource models for the mineralized zones in the Guadalupe de Los Reyes Mining District (El Zapote, Guadalupe- Laija and West, Chiripa-San Miguel, Noche Buena, and Tahonitas) included all material in the models without regard to mineability and current land position. PAH, for the resource reported here, re-tabulated mineral resources to only include those resources contained within the mining concessions held by Vista. These mineral resources are shown in Tables 17-5 and 17-6. At a cutoff grade of 0.5 g/t Au these are a total of 6.3 million tonnes of indicated resources at grades of 1.36 g/t Au and 23 g/t Ag, containing 277,600 ounces of gold and 4.7 million ounces of silver, “in situ.” At a 1.0 g/t Au cutoff grade, the indicated resources total 3.2 million tonnes at 1.97 g/t Au and 29 g/t Ag equivalent to 203,000 ounces of gold and 3.00 million ounces of silver.


17.6

In addition to the indicated resources the Vista optioned concessions contain inferred resources, which at a cutoff grade of 0.5 g/t Au, includes 3.8 million tonnes at grades of 2.01 g/t Au and 66 g/t Ag, containing 247,850 ounces of gold and 8.1 million of silver “in situ.” At a cutoff grade of 1.0 g/t Au, the inferred resources total 2.3 million tonnes at grades of 2.93 g/t Au and 94 g/t Ag, containing 214,600 ounces of gold and 7.0 million ounces of silver. TABLE 17–5 Vista Gold Corporation Guadalupe de Los Reyes Project Vista Mineral Resources (Within Gaitán Concessions) @ 0.5 g/t Au INDICATED Gold Silver INFERRED Deposit K Tonnes g/t g/t K Tonnes

Gold g/t

Silver g/t

El Zapote (*) Tahonitas Noche Buena San Miguel – Chiripa Guadalupe – Laija (*) Guadalupe – West TOTAL TOTAL CONTAINED

4,209 404 459 515 751 9 6,347 (rounded)

1.34 1.41 1.18

9.3 48.4 23.6

107 290 1,144

1.78 1.54 1.13

8.5 52.0 24.9

1.15 1.71 0.59 1.36 277,600 oz.

70.8 53.2 19.1 23.0 4,700,000 oz.

173 2,106 20 3,840

1.80 2.59 0.66 2.01 247,850 oz.

60.3 93.4 15.5 65.6 8,100,000 oz.

(*) Resource has been adjusted to reflect material removal from old u/g workings. TABLE 17-6 Vista Gold Corporation Guadalupe de Los Reyes Project Vista Mineral Resources (Within Gaitán Concessions ) @ 1.0 gt Au INDICATED Gold Silver INFERRED Deposit K Tonnes g/t g/t K Tonnes El Zapote (*) Tahonitas Noche Buena San Miguel – Chiripa Guadalupe – Laija (*) Guadalupe – West TOTAL TOTAL CONTAINED

2,117 253 231 171 438 0 3,210 (rounded)

1.93 1.82 1.62 1.90 2.44 0.00 1.97 203,000 oz.

10.6 64.6 29.0 89.0 72.2 0.0 28.8 3,000,000 oz.

62 186 492 91 1,449 0 2,280

Gold g/t

Silver g/t

2.55 2.00 1.72 2.65 3.49 0.00 2.93 214,600 oz.

9.7 67.0 33.6 68.0 123.9 0.0 94.4 7,000,000 oz.

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

The resource was based on a density of 2.6 tonnes per cubic meter for all rock material. Previously mined stope tonnages of 166,000 tonnes in the mineral envelope have been subtracted from the El Zapote resource total, while 668,000 tonnes were reduced from the Guadalupe – Laija resource. PAH checked Minorex and SRK=s resources tabulation and found that the results compared very closely. For PAH=s resource tabulation a whole block in or out approach was used with regard to the mineral envelopes and are based on the Global UTM topographic surface.


17.7

17.5.1 Vista Classified Resources The distance from the block centroid to the nearest gold composite value was used as a means of classifying the resource. SRK originally assigned an indicated resource category to blocks that were within 27 meters of a composite data value (66 percent of the total variogram range of 40 meters), with model blocks greater than 27 meters distance to an inferred category. After PAH=s review of the El Zapote and Guadalupe Laija data, it was felt that this distance could reasonably be increased. On this basis, PAH increased the distance limit for indicated resource to 30 meters and used this criteria in all subsequent resource tabulations. Inferred material was considered from 30 meters to the extend of the search distance. None of the resource was classified as measured, based on SRK’s work, which PAH believes is conservative. Figure 17-1 shows a graph of Indicated Resource tonnage variability with respect to the gold grade at different Cutoffs for the El Zapote deposit; Figure 17-2 shows the same parameters for the Tahonitas deposit; Figure 17-3 for Noche Buena deposit; Figure 17-4 for San Miguel – Chiripa deposits; and Figure 17-5 for the Guadalupe Laija deposit.

17.6

Geologic Reserves

Because there has been no prefeasibility or feasibility studies completed, with the exception of El Zapote, which is out of date, the economic viability of the resources is yet to be documented. As a result, none of the resources can be considered as mineral reserves at the present time.

17.7

Additional Resource Potential

In the El Zapote deposit, PAH notes that additional potential for mineable material exists in near surface areas of insufficient drilling and in downdip extensions of the mineralized zones. Other recognized deposits within and beyond Vista optioned concessions require additional drilling to determine strike extensions and depths of mineral concentrations.


17.8

4,500

4.50

KTonnes

4.00

Gold (g/t)

3,500

3.50

3,000

3.00

2,500

2.50

2,000

2.00

1,500

1.50

1,000

1.00

500

0.50

-

Au Grade Above Cutoff (g/t)

Tonnes (000's)

4,000

0.00 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Cutoff Grade (Au g/t)

Prepared by



9203.04

Prepared for



FIGURE 17-1

VISTA GOLD HELD INDICATED RESOURCES TONNAGE/GRADE VARIABILITY - EL ZAPOTE DEPOSIT

Date of Issue


Fig17-1.cdr

450

4.50

KTonnes

4.00

Gold (g/t)

350

3.50

300

3.00

250

2.50

200

2.00

150

1.50

100

1.00

50

0.50

-


Tonnes (000's)

400

0.00 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5


Prepared by



9203.04

Prepared for



FIGURE 17-2

VISTA GOLD HELD INDICATED RESOURCES TONNAGE/GRADE VARIABILITY - TAHONITAS DEPOSIT

Date of Issue


Fig17-2.cdr

500

4.00

KTonnes

450

Gold (g/t)

3.50

400 3.00 350

Tonnes (000's)

250


2.50

300

2.00

200

1.50

150 1.00 100

0.50

50

-

0.00 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5


Prepared by



9203.04

Prepared for



FIGURE 17-3

VISTA GOLD HELD INDICATED RESOURCES TONNAGE/GRADE VARIABILITY - NOCHE BUENA DEPOSIT

Date of Issue


Fig17-3.cdr

600

6.00

KTonnes

500

5.00

400

4.00

300

3.00

200

2.00

100

1.00

-


Tonnes (000's)

Gold (g/t)

0.00 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5


Prepared by



9203.04

Prepared for



FIGURE 17-4

VISTA GOLD HELD INDICATED RESOURCES TONNAGE/GRADE VARIABILITY - SAN MIGUEL - CHIRIPA DEPOSIT

Date of Issue


Fig17-4.cdr

800

6.0

KTonnes Gold (g/t)

700

5.0

600

4.0

400


Tonnes (000's)

500

3.0

300 2.0

200

1.0 100

-

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5


Prepared by



9203.04

Prepared for



FIGURE 17-5

VISTA GOLD HELD INDICATED RESOURCES TONNAGE/GRADE VARIABILITY - GUADALUPE LAIJA DEPOSIT

Date of Issue


Fig17-5.cdr

18.0

OTHER RELEVANT DATA AND INFORMATION

PAH completed a Prefeasibility Study on the Guadalupe de Los Reyes Project in 1998. The study contemplated only the El Zapote deposit, which was planned as an open-pit heap-leach mine based on an in-pit resource of 3.2 million tones at 1.47 g/t Au and 8.87 g/t Ag. The economic study was based on 1997 costs, operating at a capacity of 1.0 million tonnes per year, investing $12.0 million, at prices per ounce of $325 for gold and of $4.50 for silver. The study showed the property was capable of generating only marginal performance given the estimated level of reserves. Sensitivity analysis on gold prices, operating and capital costs, and life of mine appeared to indicate that a more satisfactory economic performance would be achieved by developing additional reserves. Additional mineral resources may be added at the El Zapote deposit, and have been indicated in other deposits enclosed by the concessions, including the San Miguel, Noche Buena, Tahonitas, and Guadalupe mine. It is PAH’s opinion that Vista should acquire adjacent concessions to fully cover the deposits zones that under the present conditions are constrained by the limits of optioned concessions, as is the case of the El Zapote, San Miguel, Chiripa, and Guadalupe West, and in our understanding Vista is already negotiating to acquire these other concessions. Because there has been no feasibility study completed evaluating the economic viability of the Guadalupe de Los Reyes resources documented in this report, none of the resources can be considered mineral reserves at this time.


18.1

19.0

INTERPRETATION AND CONCLUSIONS

NCM as previous owner of the Guadalupe de Los Reyes property carried out extensive exploration programs during the years 1992-2002, consisting of surveying, geologic mapping, trenching, geochemical and geophysical studies, and reverse circulation drilling. A Prefeasibility Study was completed for the El Zapote zone in 1998. Partial drilling indicated mineral resources being present in other zones within the property. Based on the previous work, the Guadalupe de Los Reyes property, as limited by the concessions under option to purchase agreement by Vista at this time, contain an indicated mineral resource, at a cutoff grade of 0.50 g/t Au, of 6.3 million tones at a grade of 1.36 g/t Au and 23 g/t Ag, and an additional inferred resource of 3.8 million tones at a grade of 2.00 g/t Au and 66 g/t Ag. This amounts to an indicated resource in-situ of 277,600 ounces of gold, and 4.7 million ounces of silver, and an inferred resource of 247,850 ounces of gold and 8.1 million ounces of silver. It is PAH’s opinion that the estimates shown in Table 17-5 and Table 17-6, have been prepared according to accepted industry standards using accepted practices, and that the work completed has been both thorough and as accurate as possible given the available database. It is PAH’s opinion that the classification of measured, indicated and inferred mineral resources as estimated herein, meet the definitions of measured, indicated and inferred mineral resources as stated by NI 43-101 and defined by the CIM Standards on Mineral Resources and Reserves Definitions and Guidelines adopted by the CIM council on August 20, 2000. The property is considered to have potential for additional resources both at depth and along strike in the veins and mineralized structures explored to date, and in other targets that have yet to be fully delineated. Acquisition of other surrounding and adjacent concessions by Vista is highly recommended to increase the amount of mineral resources for the project and eliminate possible constrain to mining. PAH also recommends additional investigation on metallurgical recoveries and specific gravity tests of deep core samples. No mineral reserves have been determined at the Guadalupe Los Reyes Project at this time, based on current information.


19.1

20.0

RECOMMENDATIONS

Further negotiations by Vista to acquire surrounding and adjacent mining concessions within the Guadalupe de Los Reyes Mining District are recommended to fully cover the identified mineralized zones, before a program of exploration is designed and developed to increase the property’s mineral resources and viability. It is recommended to investigate the possible existence of agreements by NCM or other claim owners for the use of land and water related to Project development, which may have been established with Ejido La Tasajera or any other land surface owners. It is recommended to include, in future exploration programs, drilling of the extension of the Noche Buena zone to the San Miguel – Chiripa mineralized structure. It is PAH’s belief that further drilling of the Guadalupe Laija and West, Noche Buena, Tahonitas, San Miguel and Chiripa may result in significant additional resources for the Project. Additional drilling at the El Zapote deposit may add resources to the Project. A core-drilling program should be implemented to confirm reverse circulation drill grade and structural characteristics of the Guadalupe de Los Reyes deposits. PAH recommends that additional drilling be conducted to Aprove up@ the inferred resources. In further exploration works it is recommended to include standard and blank samples for quality controls. Additional metallurgical test work should be carried out on representative samples, including large diameter core drill samples to complement the determination of crushing and/or grinding, and recovery parameters for the project. Specific gravity tests on core drill samples are also required to better support resource estimates. PAH notes that the underground workings warrant better definition, if possible, to more accurately assess location and size. PAH also notes that the occurrence of higher-grade gold grades in old mine muck in the stopes, may locally have lead to downhole contamination and remnant highergrade mineralization locally has been attributed to the grade estimation in the models. Based on the current data, PAH does not believe that either of these are major issues Currently, no reserves have been determined at this time on the Guadalupe de Los Reyes Project.


20.1

21.0

REFERENCES

1. Mr. C. W. Vaupell, February 1936. Memorandum on Guadalupe de Los Reyes Silver District. 2. García y Cisneros Asociados, By Mr. A. I. Rodríguez, November 10, 1967. Preliminary Report on Exploration Opportunities in the Guadalupe de Los Reyes District of Sinaloa, México. 3. Gordon J. Allen, P. Geol. And Brian G. Thurston, Report on the Exploration Programs on the Guadalupe de Los Reyes Property to December 31, 1997. For Minera Sierra Pacífico, S.A. de C.V., and Minera Tatema, S.A. de C.V., December 1997. 4. Dr. Matthew D. Gray, Resource Geosciences de México, S.A. de C.V., Summary Report: Geology and Gold Resource, Guadalupe de Los Reyes Project, Sinaloa, México. Prepared for Vista Gold Corporation. December 22, 2002. 5. Kappes, Cassidy & Associates, By Mr. Terence E. Albert, January 25, 1995. Guadalupe bottle roll tests. 6. McClelland Laboratorios de México, S.A. de C.V., By Mr. Raúl Mondragón, March 20, 1998. Heap Leach Cyanidation Test work – Zapote Deposit, Guadalupe de Los Reyes project, Sinaloa, México. MLM Job No. 1032. 7. Minas de San Luis, S.A. de C.V., By Departamento de Exploración, Ing. Víctor Manuel Silva Castillo,Agosto de 1989. Estudio geológico y Económico, Distrito Minero Guadalupe de Los Reyes, Municipio de Cósala, Sinaloa. 8. Minera Reyna Del Cobre, S.A. de C.V., By Mr. Enrique Gaitán Enríquez, Septiembre de 1991. Estudio Técnico-Económico de la Mina El Zapote. 9. Minores Consulting Ltd., Report on the Guadalupe de Los Reyes Property, Municipality of Cosalá, State of Sinaloa, México dated April 27, 1995. By J. Douglas Blanchflower, P. Geol., Consulting Geologist, October 30, 1995. 10. Pincock, Allen & Holt, Inc. Prefeasibility of the Zapote Deposit, Guadalupe de Los Reyes Project, Sinaloa, México. PAH Project No.9189.00. January 28, 1998. 11. Pincock, Allen & Holt, Inc. Conceptual Study for the Mariposa-Minita Project, Sinaloa, México. PAH Project No. 860.03. June 20, 1992. 12. This Technical Report was based on Mr. Stevens, Mr. Raúl Borrastero, and Mr.López opinions of the current conditions at the Project, on incorporation of the last exploration Pincock, Allen & Holt 9203.04 July 17, 2003

21.1

results developed by technical representatives and contractors for the Corporations involved in the Guadalupe de Los Reyes Project; upon review and verification of the data base and of the geologic models to determine mineral resources; and on great part of the analysis for the Project as presented on PAH’s previous reports and data base.


21.2

22.0

ADDITIONAL REQUIREMENTS FOR TECHNICAL REPORTS ON DEVELOPMENT PROPERTIES AND PRODUCTION PROPERTIES

There are no mineral reserves determined for the Guadalupe de Los Reyes project at the present time and the property is not considered a development property as defined by NI 43-101.


22.1

23.0

ILLUSTRATIONS

All corresponding illustrations for this report have been included within each section.


23.1

24.0

CERTIFICATES OF QUALIFICATION Mark G. Stevens, P.G. 274 Union Blvd., Suite 200 Lakewood, Colorado, USA Phone: 303-986-6950 Fax: 303-987-8907

I, Mark G. Stevens, P.G., am a Professional Geoscientist and Principal Geologist for Pincock, Allen & Holt of 274 Union Blvd., Suite 200, Lakewood, Colorado, USA. I am: 1.

A Professional Geologist (PG-651) in the state of Wyoming, USA, a Professional Geologist (PG-477) in the state of Washington, USA, a member of the American Institute Of Professional Geologists (CPG-08388), a member of the American Institute Of Mining, Metallurgical, and Petroleum Engineers, Inc. (SME), and a member of the Society Of Economic Geologists (SEG).

2.

I graduated from Colorado State University with a Bachelor of Science degree in geology in 1977 and subsequently obtained a Master of Science degree in geology from the University of Utah 1981, and I have practiced my profession continuously since 1981.

3.

Since 1981, I have been involved in mineral exploration and evaluation of mineral properties for gold, silver, copper, lead, zinc; in the United States, Canada, Mexico, Costa Rica, Panama, Peru, Chile, Spain, Sweden, Portugal, Kazakhstan, Russia, and Australia.

4.

As a result of my experience and qualification I am a Qualified Person as defined under the terms of N.I. 43-101.

5.

I am presently a Consulting Geologist with the international resource and mining consulting company of Pincock, Allen & Holt, and have been so since March 1988.

6.

I previously worked on the Guadalupe de Los Reyes Project, for a Pincock, Allen & Holt contract with Northern Crown Mines, from which a Prefeasibility of the El Zapote Zone was prepared. As part of this effort, I visited the project site from July 28, 1997 to July 30, 1997, for the purposes of observing site layout and infrastructure, examining the deposit geology, inspecting exploration drilling locations, reviewing available exploration and resource information and data, and discussing the project with site personnel.

7.

I have prepared the mineral resource portions of this NI43 –101report, and was assisted by the project team in the preparation of the mineral reserve part of the report, who also qualify as Qualified Persons (see certificates).


24.1

8.

I am not aware of any material fact or material change with respect to the subject matter of this preliminary assessment, which is not reflected in this report, the omission to disclose which would make this report misleading.

9.

I am independent of Vista Gold Corp. in accordance with the application of section 1.5 of National Instrument 43-101.

10.

I have read National Instrument 43-101, Form 43-101FI and this report has been prepared in compliance with NI 43-101 and Form 43-101FI.

11.

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

Dated at Lakewood, Colorado, this 17th day of July 2003.

_______________________________ Mark G. Stevens, C.P.G.


24.2

Leonel López, C.P.G. 274 Union Blvd. Suite 200 Lakewood, Colorado 80228 Phone (303)986-6950 Fax (303)987-8907 [email protected] I, Leonel López, C.P.G., am a profesional geologist and Principal Geologist for Pincock, Allen & Holt, Inc. of 274 Union Boulevard, Suite 200, Lakewood, Colorado, USA. I am: 1.

A Professional Geologist (PG-2407) in the state of Wyoming, USA, a Certified Professional Geologist (CPG-08359) in the American Institute of Professional Geologists, a registered Geological Engineer (Cédula Profesional #1191), in the Universidad Nacional Autónoma de México, a member of the International Association on the Genesis of Ore Deposits, and a member of the Association of Exploration Geochemists.

2.

I graduated from the Universidad Nacional Autónoma de México with a tittle as Ingeniero Geólogo in 1966 and subsequently have taken numerous short courses in Economic Evaluation and Investment Decition Methods at Colorado School of Mines, and other technical subjects in related professional seminars, and I have practiced my profession continuously since 1963.

3.

Since 1963, I have been involved in mineral exploration and evaluation of mineral properties for gold, silver, lead, zinc, copper, antimony, and non-metallic deposits as fluorite, barite, dolomite and coal deposits in Canada, United States of America, México, Guatemala, Costa Rica, Nicaragua, Ecuador, Venezuela, Perú, Bolivia, Chile and Argentina.

4.

As a result of my experience and qualification I am a Qualified Person as defined in NI 43101.

5.

I am presently a Consulting Geologist with the international resource and mining consulting company of Pincock, Allen & Holt, Inc. and have been an Associate since October 2002, and formerly employed from 1988 to 1993.

6.

From 1985 to 1992 I carried out exploration developments at the Mariposa mine within the Guadalupe Los Reyes mining district, including geologic mapping, sampling and underground development. The property was owned by Minera Silverado, and later by Minera Mariposa at that time. From May 20 to May 22, 2003, I visited the Guadalupe Los Reyes Project, located in the state of Sinaloa, México as an assignment from Vista Gold Corporation for the purposes of observing current infrastructure, examining the deposits geology, inspecting exploration drilling locations, reviewing available exploration and resource information and data, and discussing the project with Vista personnel.


24.3

7.

I have collaborated in the preparation of this NI 43-101 report and in the mineral resource portions, with Mr. Raúl Borrastero, Professional Geologist and with Mr. Mark Stevens, CPG, Principal Geologist and Project Manager.

8.

I am not aware of any material fact or material change with respect to the subject matter of this preliminary assessment, which is not reflected in this report, the omission to disclose which would make this report misleading.

9.

I am independent of Vista Gold Corporation in accordance with the application of Section 1.5 of National Instrument 43-101.

10.

I have read National Instrument 43-101, Form 43-101F1 and this report has been prepared in compliance with NI 43-101 and Form 43-101F1.

11.

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

Dated in Lakewood, Colorado, this 17th day of July 2003.

______________________________ Leonel López, CPG


24.4

Technical Report for the Guadalupe de Los Reyes Gold

Recommend Documents