Projects : Moss Mine; Largest Gold Resource in Arizona

*Please note: This page will be updated shortly with revised resource calculations and an updated technical report. In the meantime, please read our most recent news releases for current estimates.

NI 43-101 Amended & Restated Technical Report and PEA for Moss Mine
Northern Vertex Drill Results as of Q2 2011
Moss Resource Calculation as of Q1 2010
Moss Drill Hole Locations as of Q2 2009
Moss Column Leach Results as of Q2 2009

Description and Location of the Moss Property

Patriot has been advancing its 100% owned Moss Mine project for the past 7 years. Patriot acquired the surface and mineral rights to the property, comprising of 220 unpatented claims and 15 patented claims for over 5000 acres, in a series of transactions from 2004 through 2012. Patriot drilled 305 holes in the property for a total of 54,390 feet. The results of this and previous work show typical grades of 0.015 oz/ton to 0.088 oz/ton gold equivalent. Gold equivalents use a 1:60 gold:silver ratio. The Moss Mine Project is located within the historic Oatman District, 10 miles east of Bullhead City, Arizona and approximately 70 miles southeast of Las Vegas, Nevada. Management believes the Moss Mine project hosts the largest known gold resource in the state of Arizona.

Northern Vertex Option of the Moss Property

In March 2011 Patriot Gold Corporation entered into an agreement with Northern Vertex (NEE - TSX Venture) to advance the Moss Mine project through an aggressive exploration and development program, leading to commercial production if certain milestones and requirements are achieved. Northern Vortex has the right to earn an undivided 70% interest in the Moss Mine gold/silver property, subject to the terms of the Exploration and Option Agreement. Northern Vertex must spend an aggregate total of US$8 million on exploration and related expenditures over the next five years. Subsequent to exercise of the earn-in, Northern Vertex and Patriot will form a 70/30 joint venture.

Exploration History of the Moss Property

Discovered in 1864, the Moss Mine was the first gold discovery made in the Oatman District. Historical records show that the Oatman District produced up to two million ounces of gold. Although only minor production is recorded for the Moss Mine, several shafts and adits as well as tailings piles visible below an old mill foundation indicate the property was active into the 1930's. The Moss property then lay idle until the early 1980’s when a number of mining companies explored the district. These companies included Billiton Minerals, Magma Copper, Golconda Resources and Addwest Minerals. This work included over 35,000 feet of reverse circulation (RC) and core drilling. Patriot Gold has used the results of this work to help design its exploration program.

Gold Resource

The most significant historic mining at Moss Mine occurred on narrow veins that trend sub-parallel to the Moss Mine vein and dip steeply northerly. These veins should intersect the Moss Mine vein at depth. The company’s exploration of the Moss Property has consisted of geologic mapping, vein geochemical sampling and systematic drilling that follows the main vein mineralization down dip to determine the full extent of the identified veins.

A total of 15,218 feet in 48 holes were drilled by Patriot. All were reverse circulation (RC) except for 6 core holes. The drill holes have been angled so that they cross the vein at 90 degrees to vein dip where possible. Therefore, true widths will be 80-100% of the intercepts. Results include thick intercepts of +0.03 oz/ton gold equivalent values. Among the more exceptional values are 80 feet of 0.081 oz/ton gold equiv. in AR-7, 75 feet averaging 0.046 oz/ton gold equiv. in AR-12, 75 feet at 0.071 oz/ton gold equiv. in AR-23, 95 feet at 0.051 oz/ton gold equiv. in AR-34 and 88 feet at 0.044 oz/ton in AR-50C. Click here for complete results.

Prior to conducting a column leach study, an agitated cyanide leach study (bottle roll) was conducted to compare oxide to sulfide recoveries and determine reagent consumption. The Moss Mine deposit contains minor pyrite below a depth of approximately 200 feet. The results indicate that even the deeper, un-oxidized mineralization at Moss may be leachable. Locked cycle column leach tests were conducted by METCON Research of Tucson, Arizona on the Moss core for 109 days. The results indicate the Moss mineralization is leachable with minimal reagent consumption. Gold extraction ranged from 39 to 66 percent and silver extraction ranged from 14 to 42 percent depending on crush size. At the end of the test all three samples were still contributing gold/silver to the leach solution, indicating longer leach times will improve recoveries. Leaching is conducted for several years on the same leach pile at Round Mountain, Nevada and several other heap leach operations in Nevada. The success of this initial metallurgy indicates the Moss Mine deposit may be minable at a lower cut-off grade thus allowing mining to greater depth. Click here for complete results.

Geology of the Moss Mine Property

The project area is underlain by Tertiary quartz monzonite (a coarsely crystalline rock composed primarily of quartz, plagioclase and orthoclase) intruding Tertiary age volcanics. Precambrian basement rocks underlie the volcanics. The veins consist of quartz-calcite and lesser adularia. The Moss vein system is up to 45 feet thick and can be traced on surface for over a mile. The hanging wall of the main vein commonly has several tens of feet of stockwork veining. Dipping 40-60 degrees to the south from a high ridge, the quartz-calcite veins and stockworks are being drilled as a bulk minable gold target. Based on the results to date, Patriot believes the Moss Mine project has the potential for an economic resource of leachable gold and silver in the order of one million ounces of gold equivalent.

In March 2013 Patriot Gold Corp. updated its resource estimate performed by Metal Mining Consultants Inc., ("MMC") of Denver, Colorado, on its Moss Gold-Silver project in Mohave County, Northwestern Arizona, has resulted in an estimated 653,600 ounces of measured and indicated gold equivalent resources and 82,020 ounces of inferred gold equivalent resources.

The new resource estimate for the Moss Mine Gold-Silver Project includes:

  • 12,611,000 tonnes of Measured Resources with an average grade of 0.85 grams/tonne Au and 9.10 grams/tonne Ag, or 1.03 grams/tonne gold equivalent ("AuEq")
  • 9,978,000 tonnes of Indicated Resources with an average grade of 0.60 grams/tonne Au and 6.68 grams/tonne Ag, or 0.73 grams/tonne AuEq
  • 22,589,000 tonnes of Measured and Indicated Resources with an average grade of 0.74 grams/tonne Au and 8.03 grams/tonne Ag, or 0.90 grams/tonne AuEq

The new, updated, Moss Mine Gold-Silver Project Resource Estimate was prepared by Metal Mining Consultants Inc., ("MMC") (formerly Scott E. Wilson Consulting, Inc.) Scott E. Wilson and Dr. Stewart D. Redwood, FIMMM, both Qualified Persons as defined by NI 43-101 for those who have prepared or supervised the preparation of the scientific and technical information contained therein. CDM Smith, International Consulting Engineers independently retained by the Company, has confirmed they have reviewed and verified the new, updated, Resource Estimate. The corrected and updated resource estimates will be incorporated into a new NI 43-101 compliant technical report which will include a Preliminary Economic Assessment of the Moss Mine Gold-Silver Project co-authored by CDM Smith and MMC.

New technical information incorporated in the new estimate includes the following:
  • Drill hole information from 328 additional drill holes
  • Drilling density has been increased to approximately 15-30 meters in most parts of the deposit, thereby resulting in increased confidence in the geology required to move inferred mineral resources to measured and indicated mineral resources
  • Approximately 8,000 additional meters of drilling
  • Increase in maximum intercepts used in estimations from maximum 3 intercepts to maximum 10 intercepts
  • An additional 1,805 composite drill samples utilized for a total of 7,677-5 meter composite drill samples

Preliminary Economic Assessment

Based on the updated resource estimate and an independent technical report co-authored by CDM Smith, Inc. ("CDM") and Metal Mining Consultants Inc. ("MMC") dated March 13, 2013 (the "Technical Report"), the PEA provides an evaluation of the economics of open pit mining and heap leach processing in Phase I and Phase II production for the Moss Mine Project.

Phase II Preliminary Economic Assessment Highlights*:
  • Mine life of five years, 5,000 tpd, 42,000 AuEq oz/yr
  • Pre-tax IRR of 117.9%
  • Pre-tax payback of 15 months
  • Pre-tax NPV @5% $110 million
  • Capital expenditures $26.6 million
  • Capital/average annual AuEq oz production $633/oz
  • Cash Costs/AuEq oz $490/oz
  • Metallurgical recoveries of 75-85% for gold and 55-77% for silver
*All figures are in USD unless otherwise stated, are based on a gold price of $1,500/oz and predictions that 100% of the Phase I and II mineral resource will be minable.

The Three-Phase Mine Development Plan is designed to move the Moss Mine Project forward in a defined and thoughtful manner - from conceptual design and laboratory test work to on-site pilot plant testing (Pilot Plant – Phase I) and then onto operations (Phase II). Phase II is independent from Pilot Plant – Phase I, and will only proceed if Phase I is successful. Phase III is conceptual only, will depend on the success of Phase II, and so is not included in the PEA. Phase III would involve mine life extension and/or expansion of production volumes.

A summary of the key parameters and results of the PEA follow.

Operations Scope

Pilot Plant – Phase I
  • Designed to in-field demonstrate the economic and technical viability of heap leach processing
  • Includes pilot-scale open pit mining and heap leach processing of an aggregate of approximately 90,000 tonnes of mineralized rock
  • All activities would be confined to patented property
  • Low strip ratio 0.79:1
  • Mined zone approximately 500 feet in length
  • Both higher grade and lower grade material will be tested in Pilot Plant – Phase I
  • Production rate of 1,000 tonnes of mineralized rock / day
  • Mining and processing activities to be performed by contractors
  • Provision of a 67,463 tonne stockpile of mineralized rock for Phase II production
Operations - Phase II
  • Will proceed upon determination of successful results from Pilot Plant - Phase I
  • Would include mining and processing of approximately 6.13 million tonnes of mineralized rock
  • Open pit mining methods and heap leach processing
  • Low strip ratio 1.6:1
  • All activities would be confined to patented property
  • Pit depth ranges from 30 feet to 575 feet
  • Production and processing activities are expected to be 5,000 tonnes of mineralized rock / day
  • Mining activities to be performed by contractors and processing activities to be performed by Northern Vertex

Resource Estimates Used for Economic Assessments in the PEA:

Resources used in the economic assessment for the Moss Mine Gold-Silver Project Phase I Pilot Plant and Phase II Operations are as follows:

Resource Estimates for Phase III – Mine Life Expansion / Extension:

The anticipated operating period for Phase I is 15 months and for Phase II is five years, including development and construction. As previously stated, Phase II will only proceed upon the successful completion of Phase I.

Pilot Plant - Phase I and operations - Phase II measured and indicated resources encompass 265,000 of the total 654,000 ounces gold equivalent of global resources estimated by MMC. Upon the completion of Phase II, 389,000 ozAuEq will remain. Extending mining and processing operations onto unpatented land by mining along strike and to depth has the potential to significantly extend the life of the mine. This will be the subject of further investigation concurrent with Phase II operations. This investigation will incorporate permitting, technical, economic, and financial elements into one or more pre-feasibility and/or feasibility studies.

It should be noted that the Phase I and Phase II resources described are physically constrained to that which can be reasonably extracted by limiting mining and related facilities to patented - or private - land. The conceptual Phase III mine plan would be pursued without the physical constraints of limiting operations to patented land and will require normal course approvals from various US governmental departments and mining authorities.

Based on development of the initial resource solids containing the Phase I and Phase II resources, the mining extraction recovery rate of the in-situ resource is anticipated to be 100 percent.


Overall metallurgical data shows that ore from the Moss Mine Gold-Silver Project is readily amenable to agglomeration/heap leach cyanidation processing. Column test recoveries obtained from the bulk samples, finely crushed using rolls crushers and agglomerated using cement as a binder, ranged from 75% to 84.6% for gold and from 61.3% to 76.6% for silver. Recovery percentages are summarized in the table below:

Gold extraction was still in progress when column leach tests were terminated for purposes of completing the PEA and is expected to increase further with a longer leach cycle. Preliminary data from an ongoing column leach test indicate that the low grade mineralization will be amenable to agglomeration/heap leach cyanidation processing after roll crushing to a 95%-1/4" feed size. Use of industrial scale high pressure grinding rolls (HPGR) has the potential to improve liberation and yield higher recoveries.

The favorable results from the labatory metallurgical testing provide the basis for proceeding with the proposed field testing Pilot Plant – Phase I. Metallurgical data from the Pilot Plant program will be collected and analyzed for use in the design of operations - Phase II. Both higher grade and lower grade mineralized rock is expected to be tested in the Pilot Plant. Although positive results have been obtained to date, additional metallurgical test work will be required. Consequently, recoveries used in the PEA have been conservatively scaled back to 75% for Au and to 55% for Ag.


The Preliminary Economic Assessment recommends a continued exploration program to further delineate the mineralization at the Moss Gold-Silver Project. The limits of mineralization are still open at depth and to the west. The recommended drilling program includes additional drilling of 2,200 meters and associated costs are outlined in the table below:

Production and Economic Criteria:

The key Production and Economic Criteria outlined in the PEA are as follows:

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