Technical Report for the Guadalupe de Los Reyes Gold

Transcription

Technical Report for the
Guadalupe de Los Reyes
Gold-Silver Project,
Sinaloa, México
Prepared for
Vista Gold Corp.
August 12, 2009
100504
AMENDED AND RESTATED
December 8, 2009
Technical Report for the
Guadalupe de Los Reyes
Gold-Silver Project,
Sinaloa, México
Prepared for
Vista Gold Corp.
August 12, 2009
100504
December 8, 2009
Prepared by
Pincock, Allen & Holt
Leonel López, C.P.G.
CONTENTS
1.0
EXECUTIVE SUMMARY
1.1
1.1
1.2
1.3
1.4
1.5
1.6
Location
Ownership
Guadalupe’s History
Geology and Mineralization
Exploration and Project Data
Mineral Resources
1.6.1 Cautionary Note to U.S. Investors
Conclusions and Recommendations
1.1
1.1
1.2
1.2
1.3
1.4
1.5
1.6
INTRODUCTION AND TERMS OF REFERENCE
2.1
2.1
2.2
2.1
2.1
2.1
2.2
2.2
2.3
1.7
2.0
Page
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
4.5
4.5
4.6
4.6
ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE
AND PHYSIOGRAPHY
5.1
5.1
5.2
5.2
5.1
5.1
5.1
5.0
6.0
Accessibility
Climate and Physiography
Local Resources and Infrastructure
HISTORY
100504 December 8, 2009
6.1
i
CONTENTS (Continued)
7.0
Page
GEOLOGICAL SETTING
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
Guadalupe de Los Reyes Project Regional Geologic Setting
El Zapote Deposit Geology
Guadalupe Mine Deposit
Chiripa – San Miguel – Noche Buena Deposits
Tahonitas Deposit
El Orito Zone
El Mirador – Las Casitas
La Palmita – El Apomal
7.1
7.1
7.3
7.4
7.8
7.8
7.8
7.13
7.13
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
17.1
17.1
17.3
17.4
Introduction
Computerized Modeling
Rock Models
Grade Models
100504 December 8, 2009
ii
17.5
17.6
17.7
Page
Geologic Resources
17.5.1 Cautionary Note to U.S. Investors
17.5.2 Vista Classified Resources
Geologic Reserves
Additional Resource Potential
17.6
17.8
17.8
17.9
17.9
18.0
OTHER RELEVANT DATA AND INFORMATION
18.1
19.0
INTERPRETATION AND CONCLUSIONS
19.1
19.1
19.1
Cautionary Note to U.S. Investors
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
Mineral Resources at a Cutoff Grade of 0.50 g/t Au, as of July 31, 2009
1.5
4-1
Mining Concessions Owned or Contracted by Vista’s Subsidiary Minera Paredones
Amarillos
4.4
6-1
Summary of Historical Production
6.1
9-1
General Deposit Data
9.2
11-1
11-2
Data Verification, Meridian Gold Drill Hole Location
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
Mineralized Material Sample Identification – Head Assays
16.2
100504 December 8, 2009
iii
Page
16-2
16-3
Results of Cyanide Bottle Roll Tests
Results of Column Leach Tests
16.3
16.4
17-1
17-2
17-3
17-4
17-5
17-6
17-7
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
Difference in Resource Tabulations
Mineral Resources at Cutoff Grade of 0.50 g/t Au
Mineral Resources at a Cutoff Grade of 1.00 g/t Au
17.3
17.5
17.5
17.6
17.7
17.7
17.8
20-1
Recommendations Estimated Costs
20.1
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
7-8
Guadalupe de Los Reyes Mining District Geological Setting
El Zapote Deposit, Typical Cross Section (Looking Northwest)
Guadalupe Mine Historical Mine Workings
Guadalupe-Laija Deposit, Cross Section (Looking West)
San Miguel Deposit, Typical Cross Section (Looking Northwest)
Noche Buena Deposit, Typical Cross Section (Looking Northwest)
Tahonitas Deposit, Typical Cross Section (Looking Northwest)
El Orito Area Mineralized Structures
8-1
Epithermal Model Mineral Deposits
8.2
9-1
Drilled Mineral Deposits, Guadalupe de Los Reyes Mining District
9.3
11-1
11-2
11-3
11-4
11-5
11-6
Correlation Collar/Topography - El Zapote Deposit
Correlation Collar/Topography - Chiripa – San Miguel Deposit
Correlation Collar/Topography - Guadalupe Laija Deposit
El Zapote, Tahonitas, and 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
11.8
13-1
Guadalupe de Los Reyes Project, Check Assay Results
13.2
17-1
Indicated Resources Tonnage/Grade Variability
100504 December 8, 2009
4.2
4.3
7.2
7.5
7.6
7.7
7.9
710
7.11
7.12
17.10
iv
1.0
EXECUTIVE SUMMARY
Pincock, Allen & Holt (PAH), a division of Runge Inc., was retained by Vista Gold Corp. (Vista), to prepare
a Technical Report in accordance with US Industry Guide 7 and Canadian National Instrument 43-101,
with regard to the Guadalupe de Los Reyes (Guadalupe) gold-silver project. Guadalupe is a project in the
exploration stage. The Guadalupe 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 areas of the deposits was performed by
Meridian Gold Corporation in 2002.
In 2003, Vista acquired Mr. Enrique Gaitán (Gaitán) concessions at Guadalupe for $1.4 million and a 2
percent NSR (Net Smelter Return) royalty, which can be purchased at any time by Vista until July 31,
2053, for $1 million. In 2004, Grandcru Resources Corporation (Grandcru) acquired two groups of mining
concessions within the Guadalupe mining district with included royalty payments from 1 to 3 percent.
Vista announced completion of acquisition of the mineral rights from Grandcru and other parties in 2008,
and now controls the main area holding the mineral resources and most of the prospective area of the
Guadalupe mining district. Royalties to be paid by Vista do not exceed 5 percent at any time. This
Technical Report incorporates information reflecting the most recent project’s ownership and resource
estimates. Since 2003, Vista’s efforts have been focused on consolidating ownership of the Guadalupe
Los Reyes mining district; no additional exploration investigations have been made in the project.
1.1
Location
The Guadalupe 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 30kilometer 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
toll freeway, or can be accessed by small aircraft from a local airstrip to international airports in the cities
of Durango, Mazatlán and Culiacán.
1.2
Ownership
Vista’s agreement to consolidate ownership of the Guadalupe mining district with the various parties
involved was completed January 24, 2008, under the following terms:

Grandcru and Grupo San Miguel were paid $425,000 and $75,000, respectively, in addition to an
aggregate amount of $1,000,000, in Vista shares.

Vista agreed to pay Net Smelter Return (NSR) royalties for some of the concessions as follows:
•
To Goldcorp and its Mexican subsidiary, Desarrollos Mineros San Luis, S.A. de C.V. (DMSL): 1
percent on the San Luis concessions.
100504 December 8, 2009
1.1
•
To the San Miguel Concessions: 1 percent to DMSL and 2 percent to the San Miguel Group. The
2 percent royalty payable to the San Miguel Group can be purchased by Vista at any time for $1
million or on a pro-rated basis.
•
For the Gaitán Concessions, Vista will pay a NSR royalty to DMSL of 2 percent on gold a price at
or under $499.99 per ounce or 3 percent at a gold price of $500.00 per ounce or higher. In
addition, Vista will pay 2 percent royalty to Gaitán with an option to purchase the 2 percent
royalty for $1 million at any time before July 31, 2053.
•
For the San Luis concessions, excepting the Los Reyes Seis and the Los Reyes Siete concessions,
a pre-existing royalty agreement includes paying a 3 percent royalty to SanLuis Corporación, S.A.
de C.V. (SanLuis) in addition to 1 percent NSR to be paid to DMSL. Mining concessions Los
Reyes Seis and Los Reyes Siete only include 1 percent NSR royalty to be paid to DMSL.
•
In any case, Vista payable royalties would not exceed 5 percent NSR.
Mining concessions in México have a duration of 50 renewable years. Most of Vista’s concessions hold
duration periods to about the 2050s, except for two claims with expiration dates in 2036 and 2037.
Conditions to retain the mineral rights are through compliance of annual fees payment and presentation
of assessment work with minimum yearly investments.
1.3
Guadalupe’s History
Small-scale mining activity in the Guadalupe 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, by flotation, and by cyanidation in brick-concrete
vats.
The Guadalupe project was previously explored by a program that included regional and local geological
studies, drilling by reverse circulation (375 drill holes, 36,106 meters), 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
(PAH) Prefeasibility Report dated January 28, 1998, produced by a combination of efforts from various
specialized contracting firms under PAH lead. Assistance for the Prefeasibility Study was provided by
Gochnour & Associates in environmental studies; Steffen, Robertson & Kirsten in computer modeling and
resource estimates; Tecnoco International Corporation in metallurgical studies; and by WESTEC in
geotechnical studies, design, and costs estimates. Though not part of the Prefeasibility, other deposits
within the project area were also drilled and modeled for preliminary resource estimates, including the
Guadalupe mine (Laija and West zones), Chiripa-San Miguel- Noche Buena, Tahonitas, Mariposa, and El
Orito zones.
100504 December 8, 2009
1.2
In December 2000, the Guadalupe project was optioned 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 meters) carried out between May 16 and 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 the original concessionaires.
Subsequently, PAH prepared two Technical Reports comprising exploration activities, resource estimates,
and ownership of the Guadalupe mining district for Vista Gold Corporation dated July 17, 2003, and for
Grandcru Resources Corporation, for the Los Reyes Gold-Silver Project, dated April 11, 2005.
1.4
Geology and Mineralization
The Guadalupe project is located on 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 NeoVolcanic Belt in Central México to the Basin and Range Province in the north part of the country. This
geologic province encloses a great number of major gold and silver deposits of historic production within
mining districts of world importance, such as Hostotipaquillo, 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 percent and only occasionally up to 3
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 project includes thirteen target areas that have been identified, most occur along three
major structural zones and others within the concessions area. 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.
1.5
Exploration and Project Data
Exploration of the Guadalupe project 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 mineral resources.
100504 December 8, 2009
1.3
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.
Guadalupe’s reverse circulation drilling 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. Approximately 10 percent of
the sample intervals in the mineralized zone were sent for duplicate analysis by Min-En Laboratories to
evaluate the quality of the sample analysis. Overall, PAH found that the analytical checks results were
within standard industry practice.
The analytical results from the drilling were compiled 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.
1.6
Mineral Resources
The resulting geologic resource for the Guadalupe deposits includes all material “in situ” within the
models in Vista’s concessions boundaries, without regard to mineability. The study included data from
398 drill holes with total drilled depth of 38,838 meters and 23,938 interval samples. Most samples were
assayed by Bondar-Clegg, Min-En Laboratories and SGS-XRAL Laboratories. PAH found that the overall
check assaying was acceptable. Resource models were created by SRK and Minorex and reviewed by
PAH for the El Zapote, Guadalupe, Laija, West, La Chiripa – San Miguel, Noche Buena and Tahonitas.
Based on these estimates, under U.S. Industry Guide 7 guidelines the estimated mineralized material for
the Guadalupe project, above a 0.5 g/t Au cutoff, results in 10.0 million tonnes grading 1.50 g/t (0.048
oz/t) gold and 26 g/t (0.83 oz/t) silver.
100504 December 8, 2009
1.4
According to Canadian Institute of Mining, Metallurgy and Petroleum and CIM Definition Standards, the
Indicated Mineral Resources are estimated to be 10.0 million tonnes at a cutoff grade of 0.5 g/t (0.016
oz/t) gold with an average grade of 1.50 g/t (0.048 oz/t) gold and 26 g/t (0.83 oz/t) silver, containing “in
situ” 484,000 ounces of gold and 8.3 million ounces of silver; Inferred Mineral Resources are estimated to
be 4.9 million tonnes at 2.02 g/t (0.065 oz/t) gold and 60 g/t (1.93 oz/t) silver 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 Corp.
Guadalupe de Los Reyes Project
Mineral Resources at a CutOff Grade of 0.50 g/t Au, as of July 31, 2009
Indicated
Inferred
Deposit
K Tonnes Gold g/t Silver g/t K Tonnes Gold g/t Silver g/t
El Zapote (*)
5,723
1.37
8.80
180
1.71
7.70
Tahonitas
404
1.41
48.40
297
1.54
52.00
Noche Buena
459
1.18
23.60
1,144
1.13
24.90
San Miguel - Chiripa
2,083
1.93
58.60
664
2.38
56.60
Guadalupe - Laija (*)
751
1.71
53.20
2,106
2.59
93.40
Guadalupe West
628
1.27
25.20
497
1.53
27.30
TOTAL
Average, oz/tonne
Total Contained oz.
10,048
Rounded
1.50
25.74
0.048
0.83
484,000 8,313,900
4,888
2.02
59.98
0.065
1.93
316,800 9,425,500
(*) Resource has been adjusted to reflect material removal from old u/g w orkings.
1.6.1
“Measured resources” and “indicated resources” – U.S. investors are advised that while these terms are
recognized and required by Canadian regulations, the U.S. Securities and Exchange Commission (the
“SEC”) does not recognize them. U.S. investors are cautioned not to assume that any part or all of the
mineral deposits in these categories will ever be converted into reserves.
“Inferred resources” – we advise U.S. investors that while this term is recognized by Canadian
regulations, the SEC does not recognize it. “Inferred resources” have a great amount of uncertainty as to
their existence, and great uncertainty as to their economic and legal feasibility. It cannot be assumed
that all or any part of an inferred mineral resource will ever be upgraded to a higher category. Under
Canadian rules, estimates of inferred mineral resources may not form the basis of a feasibility study or
prefeasibility studies, except in rare cases. The SEC normally only permits an issuer to report
mineralization that does not constitute “reserves” as in-place tonnage and grade without reference to unit
measures. U.S. investors are cautioned not to assume that any part or all of an inferred resource exists
or is economically or legally minable.
100504 December 8, 2009
1.5
1.7
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 possibly improve the potential for the Project’s
economic development.
PAH believes that the exploration and sampling programs on the Guadalupe 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 tonnes and grades within acceptable accuracy limits.
Studies to gather data for the necessary environmental baseline requirements to satisfy permitting were
initiated 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 and recommends initiating environmental investigations and permitting for future
development.
PAH’S recommendations costs for additional drilling, approximately 6,000 m, transportation, technical
staff, metallurgical testworks, assaying, etc., are estimated in about $1.052 million. Please refer to
Section 20.0 of this Report for details.
100504 December 8, 2009
1.6
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 US Industry Guide 7 and Canadian National Instrument 43-101 for the Guadalupe de
Los Reyes gold-silver project (Guadalupe). PAH prepared Technical Reports for the Guadalupe de Los
Reyes gold-silver project for Vista dated July 17, 2003 and for Grandcru Resources Corporation dated
April 11, 2005. Both companies Vista and Grandcru owned part of the Guadalupe Los Reyes mining
district. The Technical Reports comprised different or adjacent areas within the Guadalupe mining district
in accordance to mining claims ownership during the time of reporting. No exploration activities have
been carried out in the project area, except for negotiations to consolidate ownership and keeping annual
tax payments current. This Amended and Restated Technical Report comprises resource estimates of
deposits identified and explored within the Guadalupe project area under control by Vista, including areas
previously owned in mining concessions by Vista and Grandcru.
Personnel assigned for this study includes the following:

Leonel López, C.P.G., Q.P., Principal Geologist and Project Manager
Other PAH personnel as required
2.2
Purpose of the Technical Report
Vista agreed with Grandcru on terms and conditions to acquire the property rights held within the
Guadalupe mining district as published on December 19, 2007. Current Vista’s property rights include
concessions that cover most of the mining district with about 6,790 hectares (16,779 acres), covering the
Guadalupe mining district area including the main exploration targets of the El Zapote, Guadalupe Mine
(Laija and West zones), Chiripa - San Miguel – Noche Buena, Mariposa, Tahonitas, El Orito deposits and
other prospective areas. PAH reviewed the concessions current status reported in Legal Opinion by
Mexico City-based Vázquez Servicios Legales, S.C. dated July 22, 2009, regarding Vista’s concessions held
through its Mexican subsidiary Minera Paredones Amarillos (MPA) within the Guadalupe de Los Reyes
mining district. 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 Northern
Crown Mines 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
100504 December 8, 2009
2.1
21, 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 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 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.
PAH prepared Technical Reports for Vista dated July 17, 2003, and for Grandcru dated April 11, 2005,
regarding the Guadalupe de Los Reyes gold–silver project. Leonel Lòpez acted as Q.P. for preparation of
these two Technical Reports and included site visits to the project’s area in 2003 and 2005.
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 Amended and Restated Technical Report by PAH did not include a site visit since no
exploration activity has taken place in the project since the last site visit performed by PAH to review the
project’s current status, infrastructure conditions, and the exploration efforts carried out by NCM and
Meridian. This site visit was performed by PAH’s representative Leonel López from May 20 to May 22,
2003, as a Qualified Person (QP), who was accompanied by Mr. Gary Parkison, consulting geologist on
behalf of Vista. Mr. Leonel López also visited the Guadalupe Los Reyes project during the period of
February 7 – 10, 2005 on behalf of Grandcru.
2.4
Terms and Definitions
Abbreviations
Unit or Term
Gaitán
Gochnour
Grandcru
Mr. Enrique Gaitán Enríquez
Gochnour and Associates
Grandcru Resources Corporation
g/t Au
grams per metric tonne
km
kilometers
100504 December 8, 2009
2.2
Luismin
Desarrollos Mineros del Pacífico, S.A. de C.V.; Minas de San Luis, S.A. de C.V. or
Desarrollos Mineros San Luis, S.A. de C.V. (DMSL), currently owned by Goldcorp
Inc.
Meridian
Minorex
mm
MPA
Meridian Gold Corporation
Minorex Consulting Ltd.
millimeters
Minera Paredones Amarillos a Mexican subsidiary of Vista
NCM
Northern Crown Mines
PAH
$Pesos
Pincock, Allen and Holt
New Pesos Mexican currency
RC
reverse circulation drilling
SRK
SanLuis
San Miguel Group
Tecnoco
tpd
Steffen, Robertson & Kirsten
SanLuis Corporación, S.A. de C.V.
Includes: Synergex Group Limited Partnership (45.25%); Genssler Investment
Partnership LLP (22.625%); Klaus Genssler (22.625%) and Douglas D. Foote
(9.5%).
Tecnoco International Corporation
metric tonnes per day
US$
US currency
Vista
Vista Gold Corporation
WESTEC
WESTEC geotechnical engineering associated
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 elevation referenced on maps and
text in this report are based on Universal Transverse Mercator and on the Map Datum NAD27-México.
100504 December 8, 2009
2.3
3.0
DISCLAIMER
This report was prepared for Vista Gold Corporation (Vista) by the independent consulting firm of
Pincock, Allen & Holt (PAH), and is based in part on information not within the control of either Vista or
PAH. Mr. Leonel Lòpez, Principal Geologist as Q.P., is responsible for the preparation of all the sections in
this Amended and Restated Technical Report, including those sections outside of his expertise in geology
and resource estimates. Those external to geology and resource estimates, were prepared by other PAH
representatives qualified in those particular disciplines (metallurgical and environmental) whose work is
believed to be reliable. While it is believed that the information contained herein is reliable under the
conditions and subject to the limitations set forth, neither Vista nor PAH guarantees their accuracy.
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).
100504 December 8, 2009
3.1
4.0
PROPERTY DESCRIPTION AND LOCATION
4.1
Property Description
The Guadalupe project includes thirteen identified main exploration target areas within the mining
district. These target areas occur along four major structural zones and in other structural zones within a
total area of about 6,000 hectares (14,830 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 and West), Tahonitas, and Noche Buena. The El Zapote zone has received the
most extensive modern exploration to date. The Guadalupe Mine, El Zapote, San Miguel, and Mariposa
deposits have previously been partially mined by underground methods.
This Technical Report presents an update of mining claims ownership and review of the mineral
resources under Vista’s control. Upon acquisition of Grandcru, Goldcorp and other third parties
concessions within the Guadalupe mining district, all mineral rights, except for two small mining
concessions (6 de Enero and Hope) are now under Vista’s control. This acquisition creates a material
change which triggers an updated Technical Report of the Guadalupe project according to Canadian NI
43-101 guidelines.
4.2
Location
The Guadalupe 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 de Los Reyes mining district are approximately:
N-24º 16´ 42" and W-106º 30´ 15" (13R 0347019-E, 2685586-N)
Elevation at the village of Guadalupe Los Reyes is 711 meters above sea level. Figure 4-1 shows a
general location map.
4.3
Project Ownership
The mineral concessions owned by Vista include 27 contiguous mining concessions in addition to one
concession application in process, covering a total surface of approximately 6,790 hectares (16,779
acres) that are all located in the Municipality of Cosalá within the State of Sinaloa, México. The exact
surface coverage will be determined once the Elota claim application has been elevated to titled
concession. These are shown in Table 4-1 and Figure 4-2.
100504 December 8, 2009
4.1
TABLE 4-1
Vista Gold Corp.
Mining Concessions Owned or Contracted By Vista's Subsidiary Minera Paredones Amarillos, August 6, 2009
Surface
INEGI
Area
Official Location Expiration
Concession Name
Title No. (hectares) Map No.
Date
Date
Royalty NSR (7)
Gaitán Concessions
La Victoria
210803 199.8708
G13C75 11/30/1999 11/29/2049 (2% - 3%) + 2% (1)
Prolongación del Recuerdo
210497
91.4591
G13C75 10/8/1999 10/7/2049 (2% - 3%) + 2% (1)
Prolongación del Recuerdo Dos
209397
26.6798
G13C75
4/9/1999
4/8/2049 (2% - 3%) + 2% (1)
Arcelia Isabel
193499
60.3723
G13C75 12/19/1991 12/18/2041 (2% - 3%) + 2% (1)
Dolores
180909 222.0385
G13C75
8/6/1987
8/5/2037 (2% - 3%) + 2% (1)
Diez de Mayo
223401
0.1842
G13C75 12/10/2004 12/9/2054 (2% - 3%) + 2% (1)
San Luis Concessions
Los Reyes 8
226037
9.0000
G13C75 11/15/2005 11/14/2055
3% + 1% (2)
G13C75 &
Loy Reyes Fracción Oeste
210703 476.9373
11/18/1999 11/17/2049
3% + 1% (2)
G13C85
Los Reyes Fracción Norte
212757 1334.4710
G13C75 11/22/2000 11/21/2050
3% + 1% (2)
Los Reyes Fracción Sur
212758 598.0985
G13C75 11/22/2000 11/21/2050
3% + 1% (2)
Los Reyes Dos
214131
17.3662
G13C75 8/10/2001 8/21/2051
3% + 1% (2)
Los Reyes Tres
214302 197.0000
G13C75
6/9/2001
9/5/2051
3% + 1% (2)
Los Reyes Cinco
216632 319.9852
G13C75 5/17/2002 5/16/2052
3% + 1% (2)
Los Reyes Cuatro
217757
11.1640
G13C75 8/13/2002 8/12/2052
3% + 1% (2)
Los Reyes Seis
225122 427.6609
G13C75 7/22/2005 7/21/2055
1% (3)
Los Reyes Siete
225123
4.8206
G13C75 7/22/2005 7/21/2055
1% (3)
San Miguel Concessions
Norma
177858 150.0000
G13C75 4/29/1986 4/28/2036
1% + 2% (4)
San Manuel
188187
55.7681
G13C75 11/22/1990 11/21/2040
1% + 2% (4)
El Padre Santo
196148
50.0000
G13C75 7/16/1993 7/15/2043
1% + 2% (4)
Santo Niño
211513
44.0549
G13C75 5/31/2000 5/30/2050
1% + 2% (4)
El Faisan
211471
2.6113
G13C75 5/31/2000 5/30/2050
1% + 2% (4)
Patricia
212775
26.2182
G13C75 1/31/2001 1/30/2051
1% + 2% (4)
Martha I
213234
46.6801
G13C75 4/10/2001
4/9/2051
1% + 2% (4)
San Pedro
212753
9.0000
G13C75 11/22/2000 11/21/2050
1% + 2% (4)
San Pablo
212752
11.1980
G13C75 11/22/2000 11/21/2050
1% + 2% (4)
Nueva Esperanza
184912
33.0000
G13C75 12/6/1989 12/5/2039
1% + 2% (4)
San Miguel
185761
11.7455
G13C75 12/14/1989 12/13/2039
1% + 2% (4)
MPA Concessions
N.A.
2353.0000
Application for title was filed in January 2008
Elota (5)
6,790.3845 hectares
16,779.34 acres
Total (6)
(1) Based on gold price: NSR at <$499.99/oz=2%; at $500.00/oz or higher=3% to be paid to Desarrollos Mineros San Luis, S.A. de C.V.
(DMSL). In addition to 2% NSR to be paid to Gaitán w ith option to purchase the 2% Royalty for $1.00 Million at any time before July 31,
2053.
(2) NSR Royalty to be paid to SanLuis Corporación, S.A. de C.V. (SanLuis) 3% in addition to 1% NSR to be paid to DMSL.
(3) NSR Royalty 1% to be paid to DMSL.
(4) NRS 1% to be paid to DMSL in addition to 2% to be paid tyo Synergex + Genssler Investments + Klaus Genssler + D.F. Foote w ith option
to purchase the 2% Royalty for $1.0 Million at any time or on pro-rated basis.
(5) Final surface to be determined by surveyor. Application by Minera Paredones Amarillos, Vista's subsidiary in process.
(6) It includes estimated Elota surface.
(7) Data from Legal Opinion, August 6, 2009.
100504 December 8, 2009
4.4
All mineral concessions in México are granted by the Dirección General de Minas (DGM) for renewable 50year terms, provided the concessions remain in good standing. 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). According to legal opinion issued by the México City-based legal office of Vázquez Servicios
Legales, S.C. dated July 22, 2009, all mining concessions owned by Vista through its Mexican subsidiary,
Minera Paredones Amarillos within the Guadalupe Project area, are current in legal status.
4.4
Guadalupe de Los Reyes Concessions Option Agreement
In 2003, Vista acquired the Gaitán concessions for $1.4 million and a 2 percent NSR royalty, which can be
purchased at any time by Vista for $1 million.
By agreement dated January 24, 2008, with Grandcru Resources and simultaneously with Goldcorp Inc.
and the San Miguel Group, Vista acquired the remaining mineral rights that cover the Guadalupe mining
district, except for two small claims located within the area. This agreement consolidates Vista’s
ownership of the mineral rights within the district, including 27 contiguous concessions and one
concession application in process of registration, with a total coverage of about 6,790 hectares (16,779
acres). Exact coverage area will be determined once the Elote claim application has been confirmed by
the DGM.
Under the Grandcru agreement, Vista has made payments for $425,000 to Grandcru and $75,000 for the
San Miguel Group and San Luis concessions, in addition to $1 million equivalent in Vista shares to the
parties. Under the terms of this agreement, Vista will pay Net Smelter Return (NSR) royalties on the
Gaitán concessions to DMSL of 2 percent if the gold price per ounce is $499.99 or lower, and 3 percent if
the price is $500.00 or higher. Vista is also obligated to pay royalties on the San Luis concessions to
DMSL (Goldcorp’s Mexican subsidiary) of 1 percent, although certain concessions have a pre-existing
royalty of 3 percent, and 1 percent is payable to DMSL on the San Miguel Group concessions in addition
to a 2 percent NSR royalty payable to the San Miguel Group, which may be purchase for $1 million at any
time or by parts on a pro-rated basis. Table 4-1 shows the royalty distribution.
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.
100504 December 8, 2009
4.5
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 also a substantiated 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. Most of the Guadalupe
area is mostly considered of interest for mining activities. However, it should be established if any
agreements between previous operators, NCM and Mr. Gaitán, and the Ejido Tasajera are still valid.
4.7
Environmental and Permitting
According to Vista 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
operations were 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 drainage. No acid drainage
from the old Guadalupe mine has been reported.
Vista will be required to apply for environmental permits to continue exploration activities and
infrastructure developments within the District.
100504 December 8, 2009
4.6
5.0
ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE
AND PHYSIOGRAPHY
5.1
Accessibility
Access to the Guadalupe project area is from approximately 100 kilometers (midway) on the toll road that
connects the cities of Mazatlán, and Culiacán of the State of Sinaloa, and then to Cosalá by a 55kilometer, two-lane paved highway. From Cosalá to the project area is a 30-kilometer 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 tropical vegetation towards the lower elevations to 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. Labor is available from these surrounding villages to Guadalupe de Los Reyes, including
Tasajera, El Saucito and Cosalá. Specialized labor would have to be brought into the Project’s area from
the cities of Culiacán, Mazatlán, Durango and other parts of the country.
The road from Cosalá through Guadalupe de Los Reyes is the only regional access to the mountains to
the southeast 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,
Culiacán and Durango, including daily international flights.
100504 December 8, 2009
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 is 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 horseback until the early 1960s when the dirt road access from Cosalá was
finally built.
Historical production for the Guadalupe 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 tonnes 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 of lesser inportance.
Total reported production and grades for the district result in a more conservative amount of
approximately 320,000 ounces of gold and 15 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 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 Corp.
Summary of Historical Production (*)
Mine
Guadalupe Los Reyes
Guadalupe Los Reyes
Minera Tatemas
El Zapote
Total Contained oz.
Period Years
1772 – 1871
1872 – 1938
1935 – 1944
Oct.88 – Feb.89
Metric Tonnes
Unknown
874,658
170,000
31,529
1,076,187
Rounded
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
(*) Based on Minas de San Luis research of production records.
100504 December 8, 2009
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, Mexican
subsidiary of Goldcorp Inc.); Minera Silverado, S.A. de C.V.; Northern Crown Mines Ltd.; Meridian Gold
Company; Grandcru Resources Corporation; and Vista Gold Corp.
100504 December 8, 2009
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, on a previous report titled,
Report on the Exploration Programs on the Guadalupe de los Reyes Property, of December 1997, on the
report titled, 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 Technical Reports on behalf of Vista and Grandcru
respectively and observations during several visits to the site, including May 20 to May 22, 2003, and
February 7 to February 10, 2005.
7.1
Guadalupe de Los Reyes Project Regional Geologic Setting
The Guadalupe de Los Reyes Project occurs in the Sierra Madre Occidental Province, a late Cretaceous to
Tertiary age volcanic sequence that extends for hundreds of kilometers from the Neo-Volcanic Belt in
central 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.
100504 December 8, 2009
7.1
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-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 1,000 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.
Main target areas identified within the Guadalupe mining district are the following:

7.2
El Zapote
Tahonitas
Noche Buena
San Miguel
La Chiripa
Mariposa
Las Primas
Guadalupe Laija
Guadalupe West
El Orito
La Palmita
El Apomal
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. 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
100504 December 8, 2009
7.3
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 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.
El Zapote deposit gold and silver mineralization is 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 further investigated. 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 meters). Figure 7-2 shows typical cross-section (5450 looking to the
NW) of the El Zapote deposit.
7.3
Guadalupe (including Laija and West Areas) 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 1,000 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 longitudinal 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.
100504 December 8, 2009
7.4
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
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.
7.6
El Orito Zone
This is located at some 4 kilometers to the north of the Guadalupe mine. It consists of an extended,
moderate to strong, argilic alteration zone. It has been explored by surface workings along an apparent
structure that shows strong oxidation, quartz veining, and kaolinization. The geologic structure crops out
within volcanic rocks of the Upper Series, with orientation to the NW 40º - 45º SE. The alteration
appears to indicate a structure with a length of about 3,000 meters.
NCM developed a drilling program with 8 RC drill holes to test the geologic extensions of the El Orito
structure to a depth of approximately 200 meters. It shows interceptions with low grade values of gold
and silver, with an occasional significant assay of up to 3 grams gold/tonne. Figure 7-8 shows El Orito
area and other mineralized zones.
100504 December 8, 2009
7.8
7.7
Preliminary field mapping indicates two mineralized fault zones outcropping to the east of the El Orito
zone. No access road exists to reach this prospective area. Both structures show argilic alteration in
orientation, NW 10º-20º SE. The structures have been recognized along 1,000 to 1,200 meters
presenting widths of 1 to 4 meters. Surface and geochemical sampling contain anomalous values for
some trace elements such as Mn, Pb, Zn, As, Au, and Ag.
7.8
La Palmita – El Apomal
These fault zones outcrop along creeks within the northern portion of Vista’s concessions. Access to
these structures is by mule or walking from the nearby Ranch of El Pino, or from El Orito area, Rancho
Las Coloradas. The structures show alteration widths that vary from 1 to 4 meters, including quartz
veining and disseminated sulfides, such as pyrite associated with propylitic alteration. Preliminary
geochemical sampling indicates anomalous results for Au, Ag and trace elements.
100504 December 8, 2009
7.13
8.0
DEPOSIT TYPES
Mineralization in the Guadalupe mining district 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 openpit mining, including the El Zapote, San Miguel, Guadalupe Mine, Tahonitas, and Noche Buena zones.
Epithermal deposits of low sulfidation type such as those found in the Guadalupe 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.
100504 December 8, 2009
8.1
9.0
MINERALIZATION
In the Guadalupe 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 the commonly banded quartz, typically of a pale yellow-green color, while
the second consisted of white crystalline quartz. It appears that the gold and silver minerals are most
commonly associated with the first stage yellow-green chalcedonic quartz. Mineralization in the Project
occurs in an area that covers approximately 5 by 2 kilometers (1,000 hectares); however, the mineralized
structures and anomalies have been extended by geologic interpretations to an area of over 6,000
hectares (14,826 acres).
In thin section studies of the host rocks, andesite to felsite are variably altered showing plagioclase
converted to potassic feldspar. In many instances the host rock is completely replaced by fine-grained
quartz or sericite with relatively abundant adularia. Gold occurs as grains that range from 5 to 30
microns and up to 230 microns (0.23 mm) in diameter. Free gold and silver minerals are observed
associated 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 most significant mineralized zones of the
Guadalupe de Los Reyes project. Figure 9-1 shows Vista claim coverage, the geologic model areas, and
drill hole locations for each of the identified deposits.
100504 December 8, 2009
9.1
TABLE 9-1
Vista Gold Corp.
General Deposit Data
Deposit
Explored Extension
Length: 1,000 meters
El Zapote
Width: 20 meters (5 to 50 meters)
Depth: 150 meter, open to depth
Drilling: 20 – 40 meter spacing (30 meters), 204 holes
Tahonitas
Resources: Within quartz zone and veins
Length: 750 meters
Depth: 125 meters, open to depth
Drilling: 33 holes at 50-meter spacing
San Miguel
Noche
Buena
Resources: Within quartz veins and quartz stringers
Open to further investigation
Width: 15 meters
Drilling: 39 holes at 70-m spacing
Resources: Within veins and stockwork
Drilling: 25 holes at 50-meter spacing
Guadalupe
El Orito
Resources: Within quartz zone and stockworks
Length: Developed by underground mining along 1,250
meters. Structure is 2,500 meters long
Width: 2-3 meter veins, within mineralized structure of
100 meters
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 meters
Resources: Two main (2 – 3 meters) veins within the
structure and stockworks, open to further investigation
Length: Outcropping 3,000 meters
Width: 1-10 meters brecciated zone
Depth: Small surface workings
Drilling: 8 holes (6 located)
Resources: Low grade intercepts, projected potential to
depth
El Mirador – Length: Unknown
Las Casitas Width: 1 to 4 meters
La Palmita
El Apomal
Depth: Outcroppings with no workings
Drilling: No drilling
Resources: Geologic prospects, no resources,
Geochemical anomaly
Length: Unknown
Width: 1 to 4 meters
Depth: Outcropping, small surface workings
Resources: Geochemical anomaly
Length: Unknown
Width: 1.20 meters
Depth: Outcroppings, fault zone in creek
Resources: Geochemical anomaly, prospective zone
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 Buena-Chiripa, 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
Structure: Outcroppings
Strike: NW 40 º- 45º SE
Dip: NE 66º- 76º
Contacts: Breccia zone with quartz veining and Feos
alteration, kaolinization
Structure: Fault zones outcroppings
Prospective areas with traces of mineralization, Requires
access road
Structure: Fault zone
Strike: NW 10º- 20º SE
Contacts: Quartz vein within structural trend, Prospective
zone
Structure: Fault zone with associated quartz vein (0.30
meters)
Strike: NW 10º SE, alteration zone, pyritization,
propilitization, coarse sulfides
Dip: NE 66º
10.0
PROJECT EXPLORATION HISTORY
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 tonnes with an average grade of 9.20 g/t gold and
430 g/t silver from the various deposits located within the mining district. Most of this production was
exported to Germany as Doré bars.
Private investors leased some of the concessions from a group of claimholders from the city of Culiacán
and carried out exploration and development operations in the Mariposa mine, resulting in extraction of
approximately 1,000 tonnes of gold ore with an average grade of 5.2 g/tonne. 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 studies including VLF-EM and Magnetic surveys,
drilling, sample and assay checks, partial underground development, and computer modeling to estimate
mineral resources. Preliminary metallurgical testwork was carried out on bulk samples and drill chips
from the El Zapote deposit. Environmental permits for exploration were obtained by NCM and Meridian.
NCM, under an option to purchase the mining claims that covered all of 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, 389 RC holes, 2,258 meters
In December 2001, Meridian optioned the project from NCM and carried out a 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
100504 December 8, 2009
10.1
Meridian subsequently dropped the option with NCM in 2002. In December 2002, NCM returned all
mineral rights for the Guadalupe de Los Reyes project to the original concessionaires, including Mr.
Enrique Gaitán, Minas de San Luis, Minera Mariposa, and a group of concessionaires from the city of
Culiacán.
Luismin has carried out prospecting studies within the concessions that cover the northern portion of the
district, including the El Orito zone, including surface and geochemical sampling along known mineralized
structures. These mineralized zones have been discovered by prospectors developing small pits and
surface workings along fault and altered zones.
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.
In 2004, Grandcru entered into agreements with Luismin and Grupo San Miguel to acquire concessions
that cover approximately 62 percent of the Guadalupe mining district. The two agreements include 20
concessions with an aggregated surface of 4,598 hectares (11,363 acres) in part of the main mining
district and surrounding area.
By agreement dated January 24, 2008, with Grandcru Resources and simultaneously with Goldcorp Inc.
and the San Miguel Group, previous owners of mineral rights included in the mining claims list, Vista
acquired the mineral rights that cover the Guadalupe mining district, except for two small claims located
within the area. This agreement consolidates Vista’s ownership of the mineral rights within the
Guadalupe district including 27 contiguous concessions with a total coverage of about 6,790 hectares
(16,779 acres).
100504 December 8, 2009
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 1 meter 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
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 drill 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.
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
100504 December 8, 2009
11.1
TABLE 11-1
Vista Gold Corp.
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
GS-02
GS-03
GS-04
GS-05
GS-06
345276
345276
345215
345218
345268
345274
2685076
2685073
2685024
2685032
2684940
2684942
690
690
715
715
730
730
345274
345274
345212
345212
345266
345266
2685069
2685069
2685031
2685031
2684943
2684943
663
663
681
681
694
694
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
-3.91
-3.91
-4.76
-4.76
-4.93
-4.93
GC-01
344106
2685280
757
344107
2685277
739
0.00
0.00
-2.38
GC-02
GC-03
GC-04
GC-05
GC-09
344104
344396
344393
344393
344503
2685280
2685304
2685309
2685306
2685315
757
723
723
723
738
344107
344395
344395
344395
344508
2685277
2685302
2685302
2685302
2685306
739
704
704
704
703
Average
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
-2.38
-2.63
-2.63
-2.63
-4.74
Chiripa
-3.72%
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.
100504 December 8, 2009
11.5
TABLE 11-2
Vista Gold Corp.
Drilling and Drill Samples Assayed(1)
Deposit
RC No. Drill Holes
Meters Drilled
Drill Samples Total
RC No. Drill Holes
Meters Drilled
Drill Samples Total (*)
RC Holes Total
Meters Drilled Total
Drill Samples Total
El Zapote
197
15,728.14
10,234
5
829.3
378
202
16,557.44
10,612
Noche
Guadalupe
San Miguel
Buena
Northern Crown Mines
78
33
25
10,547.00
3,674.35
2,592.55
6,899
2,361
1,671
Meridian Gold Inc.
9
6
0
829.2
698.2
0
9
39
0
Total Project Drilling and Assaying
87
39
25
11,376.20
4,372.55
2,592.55
6,908
2,400
1,671
Tahonitas
El Orito
Mariposa
Total
33
2,257.98
1,449
8
1,139.97
748
1
166.12
106
375
36,106.11
23,468
0
0
0
3
375.0
6
0
0
38
23
2,731.7
470
33
2,257.98
1,449
11
1,514.97
754
1
166.12
144
398
38,837.81
23,938
(1) Summary of Exploration Work by Gordon J. Allen.
* Meridian partial data available.
______________________________________________________________________________________________________________________
11.9
100504 December 8, 2009
12.0
SAMPLING METHODOLOGY
PAH reviewed the NCM reverse circulation hole sampling program for the preparation of the Prefeasibility
Report of January 1998. The sampling program consisted of collecting samples at 1.52-meter intervals (5
feet) from 133 mm (5.2 inch) diameter holes. Samples were collected from the cyclone into collection
buckets. Dry samples were split using a Jones riffle splitter, and wet samples were split using a rotary
splitter. A 5-kilogram split (approximate) was placed into a plastic sample bag for laboratory analysis.
Fifteen to twenty kilograms of the remaining material was placed in a second sample bag and saved as
the field duplicate. In a similar manner, Meridian sampling was described as collecting samples at 1.52meter 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 mineralized zones.
TABLE 12-1
Vista Gold Corp.
RC Hole Cutting Samples and Geochemical Sampling
Geochemical
Geochemical
Deposit
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
Mariposa
651
212
Other Zones
621
115
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
analyses 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 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
100504 December 8, 2009
12.1
TABLE 12-2
Vista Gold Corp.
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
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
(*) Head samples assayed by fire fusion procedures. McClelland Labs.
samples collected at approximately every fifth sample interval of the 1997 drilling (ZA-088 to ZA-197).
The density results on these cutting samples indicated a density of 2.6 grams per cubic centimeter
(equivalent to tonnes per cubic meter). The subsequent resource is calculated on the basis of this
density factor. PAH notes that these density results based on chip samples would tend to be higher
(more dense) than actual bulk tonnage because fracture and void space is not adequately accounted for.
Subsequent test work from McClelland on 16 samples from the surface metallurgical bulk samples found
that the bulk tonnage averaged 2.44 tonnes per cubic meter. PAH recommends that the bulk density
value be further substantiated in the future by samples at depth from core sampling.
100504 December 8, 2009
12.2
13.0
SAMPLE PREPARATION, ANALYSIS AND SECURITY
PAH conducted a thorough review of the NCM sampling procedures and lab processing for the
Prefeasibility Study of January 1998. Most of the project analytical samples were delivered to BondarClegg 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 250gram 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 were sent to BondarCleggs’ assay laboratory in Vancouver, British Columbia, for gold and silver analysis. For gold, a one
assay ton fire assay was conducted with an atomic absorption finish, and if the atomic absorption value
exceeds 10 g/t Au, then it was reassayed with a gravimetric finish. PAH notes that this is a typical
analytical protocol and that Bondar-Clegg is an internationally recognized laboratory.
Silver analyses of earlier drill hole samples were conducted by fire assay with an atomic absorption finish,
if silver was analyzed at all. Later drill hole samples in which silver was routinely analyzed was largely
conducted by aqua regia digestion followed by atomic absorption. The acid digestion/atomic absorption
silver values have been found to consistently be lower than the fire assay values because of a less
complete extraction of the silver from the samples. This is not a problem as long as the basis for the
silver analyses is stated when applying metallurgical recoveries. Silver analyses by acid digestion/atomic
adsorption were used for the resource calculations.
NCM had approximately 10 percent of the sample intervals in the mineralized zone sent for duplicate
analysis by a second laboratory to evaluate the quality of the sample analyses. Check assay data is
shown in Figure 13-1. Check analyses were conducted for the 1997 drilling program (ZA-088 to ZA-197)
and for the 1996 drilling program (ZA-066 to ZA-087). For this work, Bondar-Clegg supplied the sample
pulps to Min-En Laboratories (Min-En) in Vancouver, British Columbia. Min-En reportedly analyzed the
sample pulp material utilizing similar methodology as described by Bondar-Clegg.
Statistical evaluation by PAH of the 1997 drilling program, found an acceptable correlation between the
data pairs, with a lognormal correlation coefficient of 0.98 (out of 1.00). Overall, the variance between
most sample-duplicate pairs was + 30 percent and is typical of structural zone gold deposits. There was,
however, a tendency on the part of several samples for the Bondar-Clegg analysis to be significantly
higher than that from Min-En and should be investigated further. However, a comparison of the average
grades found that the Bondar-Clegg originals were about 5 percent lower than the Min-En duplicates, a
difference that is acceptable by normal engineering practice.
PAH found that for the 1996 drilling program, the correlation of the data pairs showed less correlation,
with a lognormal correlation coefficient of 0.94 (out of 1.00). Overall, the variance between most
sample-duplicate pairs was + 20 percent. PAH noted that there was a tendency, on the part of several
samples, for the Bondar-Clegg analysis to be significantly higher than that from Min-En. A
100504 December 8, 2009
13.1
comparison of the average grades of the sample pairs found that, contrary to the 1997 drilling, the
Bondar-Clegg originals were 10 percent higher than the Min-En duplicates. PAH believes that a 10
percent difference is the limit of what is acceptable by normal engineering practice.
Check analyses were also conducted on material from earlier drilling programs between 1992 and 1995
(ZA-016 to ZA-065), with original analysis largely by SGS-XRAL laboratory for drill holes ZA-016 to ZA-053
and to a lesser extent by Bondar-Clegg for drill holes ZA-054 to ZA-065, with the duplicate checks
conducted by Bondar-Clegg. 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 sampling methods and analyses representing the Guadalupe de Los Reyes
Project deposits, were generated by using procedures in accordance to accepted industry standards and
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.
Luismin geochemical assay methods and analyses were not made available to PAH.
100504 December 8, 2009
13.3
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 downhole contamination below underground workings and/or from highgrade 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 downhole 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 adding 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.
100504 December 8, 2009
14.1
15.0
ADJACENT PROPERTIES
The Guadalupe de Los Reyes Project includes eight target areas plus five exploration targets which have
been identified by NCM and other operators along four major structural zones. The Guadalupe mining
district includes the Guadalupe Mine that 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, the Tahonitas as probable southern extension of the El Zapote deposit, and the Mariposa deposit
with underground development, as well as other prospective areas such as El Orito and El Mirador. Most
of the land that encloses these deposits and other prospective areas within the Guadalupe mining district
is under Vista control, except for two small claims located in areas that may have little or no effect on
Vista’s project development.
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 (Scorpio Mining Corporation), 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
(Goldcorp Corp.).
100504 December 8, 2009
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 contacted by the leach solution.
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 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 testwork 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 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).
100504 December 8, 2009
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 Corp.
Mineralized Material Sample Identification – Head Assays (1) - Zapote Deposit
Head Assay
g/tonne
Sample No. and Location
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
1.82
20.1
(1)
(2)
Head samples assayed by fire assay fusion procedures.
Average value for bulk samples from triplicate fire assay.
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 cyanide leach
tests are summarized in Table 16-2. The average gold recovery, for 70 percent minus 2.00 mm (-10
mesh) mineral in 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, crushed to 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.
100504 December 8, 2009
16.2
TABLE 16-2
Vista Gold Corp.
Results of Cyanide Bottle Roll Tests (*)- Zapote Deposit
G/tonne
Sample
Zapote Saddle Bulk
Sample (Sample A)
Gaitán Footwall Bulk
Sample (Sample C)
Gaitán Stringer Bulk
Sample (Sample D)
Composite ZPF-01
Composite ZPF-02
Composite ZPF-03
Composite ZPF-04
Composite ZPF-05
Composite ZPF-06
Composite ZPF-07
Composite ZPF-08
Grind
-12.70 mm
-9.53 mm
-6.35 mm
-10.0 Mesh
-12.70 mm
-9.53 mm
-6.35 mm
-10.0 Mesh
-12.70 mm
-9.53 mm
-6.35 mm
-10.0 Mesh
-10.0 Mesh
-10.0 Mesh
-10.0 Mesh
-10.0 Mesh
-10.0 Mesh
-10.0 Mesh
-10.0 Mesh
-10.0 Mesh
Calc. Head
Au
Ag
3.25 15.1
3.34 16.8
3.32 16.3
3.42 13.5
2.78 19.6
2.82 12.3
2.95 18.5
2.82 14.6
1.75 31.5
1.70 24.8
1.77 29.3
1.83 26.3
2.05
2.04
1.65
1.89
1.06
1.57
1.28
2.07
17.4
12.2
13.3
12.1
14.4
25.1
8.20
23.0
Tails
Au
Ag
2.03 16.9
1.98
9.4
1.74 15.4
1.38 10.6
1.17 13.2
1.14 14.6
1.06 13.4
0.76 10.1
0.74 24.5
0.64 19.0
0.62 20.7
0.50 16.9
%
Recovery
Kg/Tonne
Au
Ag NaCN Lime
37.5 13.8
0.14
1.3
40.7 23.6
0.14
1.5
47.6 16.8
0.23
1.4
59.6 27.4
0.15
1.5
57.5 12.6
0.07
1.2
59.6 13.1
0.16
1.2
64.1 17.8
0.16
1.2
73.0 25.2
0.16
1.5
57.5 22.2
0.06
1.6
62.4 23.4
0.14
1.5
65.0 29.4
0.22
1.5
72.7 35.7
0.09
1.8
0.81
0.73
0.69
0.95
0.45
0.62
0.69
0.51
60.5
64.2
58.2
47.5
57.5
60.5
43.0
75.4
13.0
8.9
10.4
11.1
11.5
19.2
11.7
16.7
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
(*) Head Assays from Bottle Roll Tests. McClelland Lab. Report.
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 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.
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.
100504 December 8, 2009
16.3
TABLE 16-3
Vista Gold Corp.
Results of Column Leach Tests - Zapote Deposit
Assay Head % Recovery (1)
Kg/tonne
100%
Leach
Sample
minus/mm time, Days 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.
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.
100504 December 8, 2009
16.4
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 study. No further drilling was performed by NCM after 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 5- by 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 Minorex-established 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 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 the database 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 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
100504 December 8, 2009
17.1
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 minemodeling 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 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
100504 December 8, 2009
17.2
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 Corp.
Composite Statistics (Mineralized Envelope)
Number
Mean
Deposit
Type
Comp.
(g/t)
Gold
2,905
0.64
El Zapote
Silver
2,124
5.70
Guadalupe
Gold
917
1.48
Laija
Silver
1,004
44.1
Guadalupe
Gold
156
1.30
West
Silver
156
22.2
San Miguel –
Gold
246
1.34
Chiripa
Silver
289
21.0
Tahonitas
Gold
115
1.08
Silver
115
40.2
Noche Buena
Gold
208
0.97
Silver
208
21.3
Maximum
(g/t)
69.90
97.00
28.59
707.0
29.82
181.8
80.22
484.1
13.51
659.8
10.91
144.3
Minimum
(g/t)
0.00
0.00
0.04
0.80
0.05
1.00
0.04
0.80
0.00
0.90
0.06
1.00
Std. Dev.
(g/t)
2.01
6.70
2.89
80.3
2.97
17.6
5.11
20.8
1.89
78.0
1.31
22.6
Grade (g/t)
CAP-Var (*)
15.00
45.0
20.00
500
7.00
150.0
6.00
120.0
6.00
185.0
5.00
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 down-dip extension than those estimated for the El Zapote deposit.
Table 17-2 shows the kriging parameters 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 northeast-southwest 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
100504 December 8, 2009
17.3
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 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.
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.
100504 December 8, 2009
17.4
TABLE 17-2
Vista Gold Corp.
Mineral Deposits Search Interpolation Parameters Based on Variography (*)
Kriging
No.
Maximum
Ellipsoid Radius (m)
Deposit
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
Silver
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)
1
3
2
50
50
50
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.
TABLE 17-3
Vista Gold Corp.
Block Model Statistics (Mineralized Envelope) of El Zapote and Guadalupe Laija Deposits (*)
Type
No. Blocks
Mean (g/t)
Std.Dev.g/t
Minimum
Maximum
Coeff.Var.
El Zapote
Gold
60,362
0.55
0.75
0.002
7.27
1.36
Silver
64,548
5.60
4.80
0.40
45.0
0.90
Guad. Laija
Gold
23,998
1.54
2.12
0.04
16.2
1.38
Silver
24,772
53.1
86.5
0.80
639
1.63
(*) By PAH. No capping was applied by Minorex.
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 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
100504 December 8, 2009
17.5
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 Corp.
Comparison of SRK & Minorex Krige and PAH NN Block Models (Mineralized Envelope)
No. Of
Total Grade
Grade of Indicated
Grade of Inferred
Model – Deposit
Blocks
(g/t Au)
Blocks (g/t Au)
Blocks (g/t Au)
El Zapote
SRK – Kriged
60,362
0.55
0.62
0.36
PAH NN
60,362
0.52
0.61
0.25
Guadalupe Laija
Minorex Kriged
23,998
1.54
1.40
1.60
PAH NN
24,673
1.52
1.24
1.61
17.5
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.
For this Technical Report PAH re-tabulated the resources for six block models of the Guadalupe Los
Reyes deposits from the existing block models. This effort had two purposes:

Unify the Vista Gold and Grandcru resources, and
Validate the previous resource estimates.
Table 17-5 shows the percent difference between the 2009 resource tabulation and the combined 2003
tabulation. Overall, these discrepancies are minor compared to the total resources for all deposits within
the Guadalupe project and are mainly the result of rounding figures. For the resources reported here,
PAH re-tabulated mineral resources included in the Vista mining concessions.
Based on these estimates, under U.S. Industry Guide 7 guidelines the estimated mineralized material for
the Guadalupe project, above a 0.5 g/t Au cutoff results in 10.0 million tonnes grading 1.50 g/t (0.048
oz/t) gold and 26 g/t (0.83 oz/t) silver.
Indicated Mineral Resources are estimated at 10.0 million tonnes at a cutoff grade of 0.5 g/t (0.016 oz/t)
gold with average grade of 1.50 g/t (0.048 oz/t) gold and 26 g/t (0.83 oz/t) silver, containing “in situ”
484,000 ounces of gold and 8.3 million ounces of silver, and Inferred Mineral Resources estimated in 4.9
100504 December 8, 2009
17.6
TABLE 17-5
Vista Gold Corp.
Difference in Resource Tabulations (*)
Indicated Resources
Inferred Resources
K Tonnes Au g/t
Ag g/t K Tonnes Au g/t
Ag
Deposit
El Zapote
-1%
-1%
-1%
0%
-2%
Tahonitas
1%
0%
0%
-1%
-1%
Noche Buena
0%
0%
0%
0%
0%
San Miguel - Chipira
0%
0%
0%
0%
1%
Guadalupe - Laija
-13%
19%
21%
-7%
14%
Guadalupe - West
2%
-2%
0%
4%
-2%
Total Tonnes
-1%
-3%
Total Metal Contained
-1%
1%
3%
g/t
0%
-1%
0%
0%
13%
0%
3%
(*) (July 2009 Tabulation - 2003 Tabulation)/2003 Tabulation
million tonnes at 2.02 g/t (0.065 oz/t) gold and 60 g/t (1.93 oz/t) silver containing “in situ” 316,800
ounces of gold and 9.4 million ounces of silver, as shown in Table 17-6.
TABLE 17-6
Vista Gold Corp.
Indicated
Inferred
Deposit
El Zapote (*)
5,723
1.37
8.80
180
1.71
7.70
Tahonitas
404
1.41
48.40
297
1.54
52.00
Noche Buena
459
1.18
23.60
1,144
1.13
24.90
2,083
1.93
58.60
664
2.38
56.60
751
1.71
53.20
2,106
2.59
93.40
Guadalupe West
628
1.27
25.20
497
1.53
27.30
TOTAL
Average, oz/tonne
Total Contained oz.
10,048
1.50
25.74
0.048
0.83
Rounded 484,000 8,313,900
4,888
2.02
59.98
0.065
1.93
316,800 9,425,500
At a 1.0 g/t Au cutoff grade, the Indicated Resources total 5.1 million tonnes at 2.25 g/t Au and 33 g/t Ag
equivalent to 366,600 ounces of gold and 5.40 million ounces of silver “in situ”, and Inferred Resources
with 2.8 million tonnes at grades of 3.01 g/t (0.097 oz/t) gold and 87 g/t (2.80 oz/t) silver, containing
271,700 ounces of gold and 7.9 million ounces of silver “in situ” as shown in Table 17-7.
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.
100504 December 8, 2009
17.7
TABLE 17-7
Vista Gold Corp.
Indicated
Inferred
Deposit
El Zapote (*)
2,922
1.97
10.00
96
2.59
9.30
Tahonitas
253
1.82
64.60
186
2.00
67.00
Noche Buena
231
1.62
29.00
492
1.72
33.60
970
3.30
78.90
355
3.80
75.80
438
2.44
72.20
1,449
3.49
123.90
Guadalupe West
247
2.19
31.20
229
2.53
35.20
TOTAL
Average, oz/tonne
Total Contained oz.
5,061
2.25
33.22
0.07
1.07
Rounded 366,600 5,405,400
2,807
3.01
87.06
0.10
2.80
271,700 7,857,200
17.5.1
17.5.2
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 in 2003, 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 criterion
in all subsequent resource tabulations. Inferred material was considered from 30 meters projected to the
100504 December 8, 2009
17.8
full extent of the search distance. None of the resources were 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 all the Guadalupe de Los Reyes project estimated deposits.
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 Vista concessions require additional drilling to determine strike extensions and depths of
mineral concentrations.
100504 December 8, 2009
17.9
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 tonnes 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, Chiripa, Noche Buena, Tahonitas, and
Guadalupe mine, Guadalupe West and Laija. It is PAH’s opinion Vista’s acquisition of all the adjacent
concessions fully covers the deposits zones increasing the estimated mineral resources held within the
Guadalupe mining district.
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.
100504 December 8, 2009
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, within the concessions owned by
Vista, based on these estimates and under U.S. Industry Guide 7 guidelines the estimated mineralized
material for the Guadalupe project, above a 0.5 g/t Au cutoff is 10.0 million tonnes grading 1.50 g/t
(0.048 oz/t) gold and 26 g/t (0.83 oz/t) silver.
Indicated Mineral Resources are estimated at 10.0 million tonnes at a cutoff grade of 0.5 g/t (0.016 oz/t)
gold with average grade of 1.50 g/t (0.048 oz/t) gold and 26 g/t (0.83 oz/t) silver, containing “in situ”
484,000 ounces of gold and 8.3 million ounces of silver, and Inferred Mineral Resources estimated in 4.9
million tonnes at 2.02 g/t (0.065 oz/t) gold and 60 g/t (1.93 oz/t) silver containing “in situ” 316,800
ounces of gold and 9.4 million ounces of silver.
It is PAH’s opinion that the estimates shown in Table 17-6 and Table 17-7, 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.
19.1
100504 December 8, 2009
19.1
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. Additional exploration targets have been identified within the claimed area, which require of
more detailed investigations. 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.
100504 December 8, 2009
19.2
20.0
RECOMMENDATIONS
Upon Vista’s acquisition of all the Guadalupe mining district concessions, further exploration and
investigations are required to fully evaluate the project’s geologic potential. Other exploration targets
have been identified within the district, which may increase the property’s mineral resources and viability.
It is recommended that investigations be conducted into 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 that, in future exploration programs, drilling include 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. Estimated costs for the suggested exploration programs is included in Table 20-1.
TABLE 20-1
Vista Gold Corp.
Recommendations Estimated Costs
Estimated Costs
Concept
US $
Drilling, approx. 6,000 meters
720,000
Geologic Staff, approx. 6 months
104,000
Vehicles
44,000
Camp Facilities
13,000
Metallurgical Testworks
75,000
Assays
30,000
Land Holdings / Legal
66,000
Total
1,052,000
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 increase certainty of the inferred resources.
In further exploration works, it is recommended that standard and blank samples for quality controls be
included.
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.
100504 December 8, 2009
20.1
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 higher-grade 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 for the Guadalupe de Los Reyes Project.
100504 December 8, 2009
20.2
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, México.
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. Pincock, Allen & Holt, Inc. Technical Report for the Guadalupe de Los Reyes Gold - Silver Project,
State of Sinaloa, Western México. Prepared for Vista Gold Corp. PAH Project No. 9203.04. July 17,
2003.
100504 December 8, 2009
21.1
13. Pincock, Allen & Holt, Inc. Technical Report Los Reyes, Gold – Silver Project, State of Sinaloa,
Western México. Prepared for Grandcru Resources Corp. PAH Project No.9412.00 April 11, 2005.
14. Legal Opinion by the México City-based Vázquez Servicios Legales, S.C. legal office dated July 22,
2009.
100504 December 8, 2009
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.
100504 December 8, 2009
22.1
23.0
ILLUSTRATIONS
All corresponding illustrations for this report have been included within each section.
100504 December 8, 2009
23.1
24.0
CERTIFICATE OF QUALIFIED PERSONS
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 Professional Geologist and Principal Geologist for Pincock, Allen & Holt, Inc.
of 165 South Union Boulevard, Suite 950, 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 and Founding
Member at SME (#1943910), registered Geological Engineer (Cédula Profesional #1191), in the
Universidad Nacional Autónoma de México, a member of the Society of Economic Geologists, a
member of the International Association on the Genesis of Ore Deposits, a member of the
Geological Society of America and a member of the Association of Exploration Geochemists.
2.
I graduated from the Universidad Nacional Autónoma de México with a title 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. I have been involved at various occasions
with the Guadalupe de Los Reyes mining district since 1985.
4.
As a result of my experience and qualification I am a Qualified Person as defined in NI 43-101.
5.
I am presently a full time employee and Consulting Geologist with the international resource and
mining consulting company of Pincock, Allen & Holt, Inc. and have been employed 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
100504 December 8, 2009
24.1
preparing an NI 43-101 Technical Report and 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. I participated and
was responsible for preparation of Technical Report of the Los Reyes project in the Guadalupe de
Los Reyes mining district for Grandcru Resources Corp. dated April 11, 2005, including site visit to
the Guadalupe Los Reyes project’s area during the period of February 7 – 10, 2005. I was
responsible and acted as QP in the preparation of both of these Technical Reports.
7.
I am the primary author of the report entitled “Technical Report for the Guadalupe de Los Reyes
Gold-Silver Project, Sinaloa, Mexico,” dated August 12, 2009, as amended and restated. I am
responsible for all report sections including those report sections outside of my discipline of geology
and resource estimates, which were prepared by other Pincock Allen and Holt representatives that
were qualified in those particular disciplines (metallurgical and environmental), which I believe to
be reliable work. I have visited the project in July 2003 and in February 2005 and I have acted as
Project Manager for the preparation of this Amended and Restated Technical Report, for which no
exploration activity has taken place since 2005.
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 8th day of December 2009.
“Leonel López”
______________________________
100504 December 8, 2009
24.2