Commonwealth Silver and Gold Mining Inc.

Commonwealth Silver and Gold Mining Inc.

February 13, 2014 13:12 ET

Commonwealth Silver and Gold Completes Positive Preliminary Economic Assessment for the Commonwealth Project, Cochise County, Arizona

TORONTO, ONTARIO--(Marketwired - Feb. 13, 2014) - Commonwealth Silver and Gold Mining Inc. ("Commonwealth Silver and Gold" or the "Company") is pleased to provide the results that will be reported in its Preliminary Economic Assessment ("PEA") for the 98% controlled Commonwealth gold and silver project in Cochise County, Arizona, approximately 120 km (75 miles) southeast of Tucson. The PEA was completed in accordance with National Instrument 43-101 ("NI 43-101") by Hard Rock Consulting, LLC ("HRC") of Lakewood, Colorado. All dollar amounts are in United States dollars unless otherwise stated.

All NPV amounts, IRR and payback period are based on the Company's 98% share of Project economics. All mining statistics, production, capital and closure amounts are to 100%. Highlights from the base case study at $1,350 per ounce gold, $22.50 per ounce silver and based solely on estimated Measured and Indicated mineral resources include:

  • Pre-tax Net Present Value ("NPV") at a 5% discount rate of $141.0 million and a pre-tax Internal Rate of Return ("IRR") of 74.9%;
  • After-tax NPV at a 5% discount rate of $101.3 million and IRR of 58.2%;
  • After-tax payback of 1.6 years;
  • Pre-production capital cost ("CAPEX") of $27.2 million including a 20% contingency;
  • Remaining advance royalty payment $4.1 million and start-up working capital of $13.5 million until positive cash flow from leaching is achieved;
  • Sustaining capital of $20.6 million (100%) over life of mine ("LOM") including a 20% contingency and reclamation, net of salvage values of $8.4 million;
  • An 8.7 year mine life, mining and processing 31.2 million tonnes of ore at 10,000 tpd, averaging 0.39 grams per tonne ("g/t") gold and 32.0 g/t silver;
  • An overall strip ratio of 0.97:1;
  • Average annual payable metal production of 35,800 ounces of gold and 1.3 million ounces of silver for total LOM production of approximately 312,000 ounces of gold and 10.9 million ounces of silver;
  • Average annual gold equivalent ("AuEq") production of 57,000 ounces AuEq at 60:1 gold to silver ratio, peaking at approximately 69,000 ounces AuEq in year 7;
  • Gold Institute Cost Standard, LOM total cash operating costs are estimated to be approximately $831 per gold equivalent ounce;
  • The HRC PEA has been constrained to the mineral resource estimate contained within a pit located entirely on the Company's patented mining claims and does not take into account the potential for additional mineralization on the adjoining unpatented mining claims or the potential for mineralization at the nearby Blue Jeep and San Ignacio exploration targets, all of which have the potential to extend the current projected life of the overall project or augment the economics of future years. Currently, there are no additional estimated mineral resources on any of these areas that are in compliance with NI 43-101.

Michael Farrant, President and CEO stated, "We are extremely pleased with this Preliminary Economic Assessment. It demonstrates that the Commonwealth Project is one of the best undeveloped precious metals projects in the world based on after-tax IRR and after-tax NPV relative to the capital required to put the Project into production. The Project sits on private land in a mining friendly jurisdiction surrounded by first rate infrastructure. Most importantly, given the size of the Project relative to the market capitalization of the Company, this is a Project that can get built and those are exactly the kinds of projects that are retaining a superior valuation in the changing global mining landscape. The Commonwealth Project is currently projected to become the largest operating gold mine in the state of Arizona. As a Company, we have continued to deliver against our originally stated plans and I am very pleased with the work performed by everyone that contributed to the completion of this PEA."

The sensitivity table below shows the pre-tax and after-tax NPV, IRR and payback period at different gold prices, with the corresponding silver price calculated at a 60:1 gold to silver ratio.

Au Price Per Ounce

Ag Price Per Ounce

Pre-tax NPV ($M)

After-tax NPV ($M)


After-tax IRR
Pre-tax Payback (Years) After-tax Payback (Years)
$ 1,050 $ 17.50 $ 34.2 $ 22.3 24.7 % 18.6 % 2.6 5.2
$ 1,125 $ 18.75 $ 60.9 $ 42.7 38.2 % 29.6 % 2.2 2.5
$ 1,200 $ 20.00 $ 87.7 $ 62.4 50.9 % 39.6 % 1.8 2.1
$ 1,275 $ 21.25 $ 114.3 $ 81.8 63.1 % 49.1 % 1.5 1.8
$ 1,350 $ 22.50 $ 141.0 $ 101.3 74.9 % 58.2 % 1.3 1.6
$ 1,425 $ 23.75 $ 167.7 $ 120.4 86.5 % 67.0 % 1.0 1.4
$ 1,500 $ 25.00 $ 194.4 $ 138.7 97.9 % 75.1 % 1.0 1.3
$ 1,575 $ 26.25 $ 221.1 $ 156.4 109.1 % 82.4 % 0.8 1.1
$ 1,650 $ 27.50 $ 247.7 $ 174.1 120.3 % 89.7 % 0.7 1.0
Table 1: Mine Plan Highlights
Summary of Results Unit Value
Mine Life Years 8.7
Total ore to leach pads M tonnes 31.2
Total waste M tonnes 30.3
Strip ratio w:o 0.97:1
Total re-handled M tonnes 5.3
Total moved M tonnes 66.8
Ore mining rate tpd 10,000
Average grade to pad - Au g/t 0.39
Average grade to pad - Ag g/t 32.0
Cumulative recovery - Au % 79.5%
Cumulative recovery - Ag % 34.2%
LOM production - Au ounces 311,534
LOM production - Ag ounces 10,926,367
LOM production - AuEq (60:1) ounces 493,640
Average annual production - Au ounces 35,809
Average annual production - Ag ounces 1,255,904
Average annual production - AuEq (60:1) ounces 56,740
Table 2: Economic Highlights
Summary of Results Value ($ M) $/oz AuEq
LOM revenue - ($1,350/oz. Au, $22.50/oz. Ag) $666.4 $1,350
LOM operating costs:
Mining (including 2.5% contingency) 182.2 369
Processing (including 2.5% contingency) 190.9 387
Site G&A (including 2.5% contingency) 19.9 40
Property and other taxes 5.3 10
Royalties 8.2 17
Transportation and refining 3.8 8
Total LOM cash operating costs 410.3 831
Capital and closure costs:
Pre-production capital 23.0 46
Pre-production contingency (20%) 4.2 9
Total pre-production capital 27.2 55
Sustaining capital 17.2 35
Sustaining capital contingency (20%) 3.4 7
Total sustaining capital 20.6 42
Closure costs net of salvage values 8.4 17
Total capital and closure costs (including contingency) 56.2 114
Other cash outflows:
Income taxes 53.5 108
Other 4.1 8
Total after-tax cash flow $142.3 $289
Unit costs Unit Value
Cost per tonne mined - 61,426,774 tonnes $/tonne $2.97
Cost per tonne processed - 31,153,575 tonnes $/tonne $6.13
Cost per tonne site G&A - 31,153,575 tonnes $/tonne $0.64

Mineral Resource Statement for the Commonwealth Gold and Silver Project:

The Mineral Resource estimate, before designing an engineered pit, is based on a 3D geologic model constructed using geologic and assay data from approximately 23,085 meters of drilling in 208 drill holes (155 historic and 43 drilled by the Company) and 2,984 meters of channel sampling in 209 channel sample lines. The assay data was examined for the presence of high grade outlier data which could potentially adversely impact the grade estimation. Based on this analysis, all gold and silver assays were capped at 10.0 g/t and 1,000.0 g/t, respectively. The capped assay data were then composited into 4.0m down-hole lengths for use in grade estimation. Block grades were estimated using inverse distance weighting ("IDW") interpolation methods, specifically ID2.5. The Mineral Resource estimate stated above a 0.2 g/t gold equivalent ("AuEq") cut-off grade is stated below in Table 3.

Table 3: Mineral Resource Statement for the Commonwealth Gold-Silver Deposit, Cochise County, Arizona, Hard Rock Consulting, LLC, November 30, 2013*
Contained Metal (Ounces)
Cut-off (g/t) Tonnes ('000) Au
Grade (g/t)
Grade (g/t)

Inverse Distance 2.5 Model In Pit Measured Resources
0.4 4,069 0.57 48.6 1.38 74,800 6,357,700 180,800
0.3 4,504 0.53 45.0 1.28 77,200 6,516,900 185,700
0.2 5,007 0.49 41.3 1.18 79,000 6,648,500 189,800
Inverse Distance 2.5 Model In Pit Indicated Resources
0.4 21,934 0.45 36.8 1.06 314,500 25,950,900 746,100
0.3 26,643 0.40 32.2 0.93 339,200 27,582,000 799,200
0.2 30,623 0.36 29,1 0.85 354,400 28,650,600 832,000
In Pit Measured and Indicated Resources
0.4 26,003 0.47 38.6 1.11 389,300 32,308,600 926,900
0.3 31,147 0.42 34.1 0.98 416,400 34,098,900 984,900
0.2 35,630 0.38 30.8 0.89 433,400 35,299,100 1,021,800
Inverse Distance 2.5 Model Inferred Resources
0.4 7,380 0.29 17.2 0.58 67,900 4,075,100 136,700
0.3 12,974 0.25 13.8 0.48 102,800 5,762,000 199,600
0.2 18,733 0.21 11.6 0.41 127,600 6,998,200 245,400
(1) Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the Mineral Resources estimated will be converted into Mineral Reserves.
(2) Measured and Indicated Mineral Resources captured within the pit shell meet the test of reasonable prospect for economic extraction and can be declared a Mineral Resource.
(3) Inferred Mineral Resources are that part of the Mineral Resource for which the quantity and grade or quality are estimated on the basis of geological evidence and limited sampling and reasonably assumed, but not verified, geological and grade continuity.
(4) All resources are stated above a 0.2 g/t gold equivalent ("AuEq") cut-off.
(5) Pit optimization is based on assumed gold and silver prices of US$1,350/oz. and US$22.50/oz., respectively and mining, processing and G&A costs of US$7.25 per tonne. Metallurgical recoveries for gold and silver were assigned by lithologic unit.
(6) Mineral resource tonnage and contained metal have been rounded to reflect the accuracy of the estimate, and numbers may not add due to rounding.
(7) Gold Equivalent stated using a ratio of 60:1 and ounces calculated using the following conversion rate: 1 troy ounce = 31.1035 grams. Metallurgical recoveries are not accounted for in the gold equivalent calculation.

Mineral Resource Estimates Used for Economic Assessment in the PEA:

The estimated Mineral Resource contained within the PEA includes 28.3 million tonnes at a 0.3 g/t AuEq cut-off and an additional 2.8 million tonnes of lower grade ore at a 0.24 g/t AuEq cut-off and is presented in Table 4. This represents the estimated Mineral Resource contained within the preliminary engineered pit design which includes haul roads. The PEA is preliminary in nature and it is important to note that the Mineral Resources described herein are not mineral reserves and, as such, do not have demonstrated economic viability. There is no certainty that the preliminary economic assessment will be realized.

Table 4: Measured and Indicated Resources within Pit Design
Contained Metal (Ounces)
Pit Phase Resource Category Tonnes ('000) Au



Phase 1 Measured 3,253 0.46 43.07 1.18 48,034 4,504,874 123,115
Phase 1 Indicated 12,227 0.36 34.57 0.94 142,539 13,590,165 369,042
Phase 1 Measured + Indicated 15,480 0.38 36.36 0.99 190,573 18,095,039 492,157
Phase 2 Measured 1,633 0.56 38.17 1.19 29.212 2,003,915 62,610
Phase 2 Indicated 14.040 0.38 26.37 0.82 172,644 11,902,972 371,027
Phase 2 Measured + Indicated 15,673 0.40 27.60 0.86 201,856 13,906,886 433,637
Total All Phases Measured 4,886 0.49 41.43 1.18 77,245 6,508,788 185,725
Total All Phases Indicated 26,267 0.37 30.19 0.88 315,184 25,493,137 740,069
Total All Phases Measured + Indicated 31,154 0.39 31.95 0.92 392,429 32,001,925 925,794
1) Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the Mineral Resources estimated will be converted into Mineral Reserves.
2) Prepared by Jeff Choquette, P.E., Mining Engineer, an independent Qualified Person within the meaning of NI 43-101, using a reporting cut-off grade of 0.24 g/t AuEq.
3) Gold Equivalent stated using a ratio of 60:1 and ounces calculated using the following conversion rate: 1 troy ounce = 31.1035 grams. Metallurgical recoveries are not accounted for in the gold equivalent calculation.

*Total Measured and Indicated ("M&I") resources are inclusive of the M&I resources limited to the optimized ultimate pit boundary and as such Table 4 summarizes resources contained within the pit design only.

Mining and Crushing

The mine plan developed for the PEA mines the Commonwealth deposit in two phases. The phase one pit containing 15.48 million ore tonnes is mined during years 1 to 4. During years 1 to 3, the average strip ratio is 0.66:1. During year 4, mining begins to transition into the phase two pit containing 15.67 million ore tonnes. The average strip ratio over years 4 to 6 is 1.66:1 while during years 7 to 9 the average strip ratio falls to 0.42:1.

Standard open pit mining methods are utilized involving typical drilling, blasting and material movement. The 31.2 million ore tonnes to be placed on the leach pads are comprised of five different rock types. Three of these rock types comprising 19.43 million ore tonnes (62%) are required to be crushed to 1/2 inch. Two of these rock types comprising 11.72 million ore tonnes (38%) are required to be crushed to 1/8 inch and agglomerated.

Table 5: Crush Size, Recovery and Ore Tonnage by Rock Type
Recoveries (%)
Rock Type Crush Size Au Ag Tonnes (M)
Rhyolite 1/8" 78.0 30.0 7.34
Vein 1/8" 79.0 49.0 4.38
Lower Andesite 1/2" 81.0 33.0 4.63
Upper Andesite 1/2" 78.0 35.0 6.11
Bisbee 1/2" 80.0 23.0 8.69
Total 79.5 34.2 31.15

The Company received a quote from a contractor to perform all of the drilling, blasting, material movement and crushing to mine plan specifications. This quote has been included in the PEA.


The Commonwealth Project will use a (flow rate) Merrill-Crowe gold and silver recovery plant using zinc precipitation to recover gold and silver from cyanide solution. The process plant will operate 24 hours per day and 365 days per year at a rate of 3,000 gallons per minute. The process plant will produce doré with approximately 97% of the precious metal content being silver and 3% being gold.


The Commonwealth Project is accessible by paved highway. Currently a 14.4 KvA powerline services the property with 60 amp service. The PEA envisions upgrading the trunk powerline from the Apache Generating Station located 19km (11 miles) from the Project site at a cost of approximately $358,000. Water is planned to be sourced from regional groundwater sources.

Capital Costs

The initial capital requirement for the Project to 100% is estimated to be $27.2 million, sustaining capital of $20.6 million and net closure costs of $8.4 million as detailed in the table below. A contingency of $7.6 million is included in the $56.2 million total.

Table 6: Commonwealth Project Capital and Closure Costs
Capital and Closure Costs $ (millions)
Pre-production Capital Costs
Conveying equipment 4.8
Merrill-Crowe plant and equipment 2.5
Truck shop, assay lab and buildings 4.5
Haul roads and access road 1.2
Leach pad and ponds 4.9
Off-site infrastructure 0.7
Owner's cost and indirects 3.1
Surface rights 1.3
Total pre-production initial capital costs 23.0
Contingency 4.2
Total pre-production capital costs 27.2
Sustaining Capital Costs
Leach pads 8.9
Merrill-Crowe plant and equipment 8.3
Contingency 3.4
Total sustaining capital 20.6
Reclamation and closure costs 12.3
Salvage values - mine and other (2.6)
Salvage values - land (1.3)
Closure costs net of salvage values 8.4
Total capital and closure costs 56.2

Financial Analysis and Sensitivities

Using a gold price of $1,350 per ounce and a silver price of $22.50 per ounce, the PEA yields a pre-tax NPV at 5% of $141.0 million and IRR of 74.9% with a payback period of 1.3 years. After-tax NPV at 5% amounts to $101.3 million, and IRR of 58.2% and a payback period of 1.6 years.

Table 7: Project NPV Sensitivity to Discount Rates
Discount Rate Pre-tax NPV After-tax NPV
0% $195.8 $142.3
5% $141.0 $101.3
8% $115.6 $82.0
10% $101.3 $71.2

Qualified Persons and Contributors

The Technical Report and Preliminary Economic Assessment for the Commonwealth Silver and Gold Project was prepared by Hard Rock Consulting, LLC of Lakewood, Colorado, with the following Qualified Persons, as defined by NI 43-101, each of whom is independent of the Company, contributing to their respective sections:

Qualified Persons

Zachary Black - QP-SME-RM, Geology, Resource Modeling

J. J. Brown - P.G., QP-SME-RM, Geology, Overall Report Content

Jeff Choquette - P.E., QP-MMSA, Mine Planning, Economic Modelling, Mine Management

Deepak Malhotra, Resource Development Inc - Ph.D., QP-MMSA, Metallurgy

Additional Contributors:

Don Beesley - B.Sc., Project Management, Scheduling, Estimating

Mark Shonnard - B.A. (Hons), CPA, Economic Modeling, Financial Analysis

Kenn Zerby - B.Sc., Mechanical Engineering, Graphics and Drafting

Each of the consultants has reviewed and approved this news release. In addition, the foregoing technical information has also been reviewed by Mr. Hall Stewart, Vice President, Exploration for Commonwealth Silver and Gold and a Qualified Person for the purpose of NI 43-101.

Technical Report

A copy of the full NI 43-101 Technical Report will be available on the Company's website at within 45 days.

About Commonwealth Silver and Gold Mining Inc.

Commonwealth Silver and Gold is a private Canadian mineral exploration and development company focused on acquiring gold and silver properties in politically stable, mining friendly jurisdictions and advancing its flagship Commonwealth Project in Arizona towards production. The Company comprises an experienced management group with a strong background in acquisition, exploration, development and financing of precious metals mining projects.

For further information on Commonwealth Silver and Gold please visit


Information concerning the properties of Commonwealth Silver and Gold has been prepared in accordance with Canadian standards under applicable Canadian securities laws and may not be comparable to similar information for United States companies. This news release uses the terms "Mineral Resource", "Measured Mineral Resource", "Indicated Mineral Resource" and "Inferred Mineral Resource" which are Canadian mining terms as defined in and required to be disclosed by NI 43-101 under guidelines set out in the CIM standard "CIM Definition Standards - For Mineral Resources and Reserves". While the terms "Mineral Resource", "Measured Mineral Resource", "Indicated Mineral Resource" and "Inferred Mineral Resource" are recognized and required by Canadian regulations, they are not defined terms under standards of the United States Securities and Exchange Commission (the "SEC"). The estimation of measured and indicated Mineral Resources involves greater uncertainty as to their existence and economic feasibility than the estimation of proven and probable reserves. U.S. investors are cautioned not to assume that measured and indicated Mineral Resources will be converted into reserves. The estimation of inferred Mineral Resources involves far greater uncertainty as to their existence and economic viability than the other categories of estimated Mineral Resources. 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 feasibility or other economic studies. Readers are also cautioned not to assume that all or any part of Measured or Indicated Resources will ever be converted to Mineral Reserves. Additionally, readers are cautioned not to assume that all or any part of an "Inferred Mineral Resource" exists, or is economically mineable.

Disclosure of "contained ounces" in an estimated Mineral Resource is permitted disclosure under Canadian regulations, however the SEC normally only permits issuers to report mineralization that does not constitute "reserves" by SEC standards as in place tonnage and grade without reference to unit measures. Accordingly, the information contained in this news release may not be comparable to similar information made public by U.S. companies that are not subject to NI 43-101.


This news release contains certain "forward-looking information" under Canadian securities laws. All statements that address future plans, activities, events or developments that the Company believes, expects or anticipates will or may occur are forward-looking information. This can include, but is not limited to comments regarding the timing and content of upcoming work programs, geological interpretations, receipt of property titles, potential mineral recovery processes etc. Forward-looking information addresses future events and conditions and therefore involves inherent risks and uncertainties. There can be no assurance that outcomes anticipated in the forward-looking information will occur and actual results may differ materially from those currently anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking information. The Company undertakes no obligation to update publicly or otherwise any forward-looking information, except as may be required by law.

No stock exchange, regulation securities provider, securities commission or other regulatory authority has approved or disapproved the information contained in this news release.

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