SOURCE: International Minerals Corporation

International Minerals Corporation

December 19, 2011 18:00 ET

International Minerals Announces Positive Preliminary Economic Assessment at Converse Gold Project, Nevada

SCOTTSDALE, AZ--(Marketwire - Dec 19, 2011) - International Minerals Corporation (TSX: IMZ) (SWISS: IMZ) announces positive results of an independent Preliminary Economic Assessment ("scoping study") for its 100%-owned Converse gold deposit ("Converse") in northern Nevada.

At base-case gold and silver prices of $1,300 per ounce ("/oz") and $25/oz respectively and a 45,000 tonnes per day ("tpd") throughput, an open-pit mining project at Converse could return a pre-tax non-discounted cash flow of approximately $494 million over a 14 year mine-life, based on conceptual mine production of 217 million tonnes ("Mt") at an average grade of 0.52 grams per tonne gold and 3.9 g/t silver.

Subject to final IMZ Board approval, based on the results of this scoping study, IMZ intends to commence a full feasibility study for Converse in 2012.

Highlights of Scoping Study (All currency in US dollars: tonnes or grams per tonne are metric)

  • Base-case metal prices: $1,300/oz gold and $25/oz silver.

  • Conceptual mine production: 217 Mt at an average grade of 0.52 g/t gold and 3.9 g/t silver (or 0.58 g/t gold equivalent), containing 3.60 million ounces ("ozs") gold and 27.6 million ozs silver.

  • Recovered ozs: 2.17 million ozs gold and 8.47 million ozs silver (or approximately 2.33 million ounces of gold equivalent) using average expected metallurgical recoveries of 60% for gold and 31% for silver.

  • Conceptual process throughput of 45,000 tpd (16.5 million tonnes per year) from an open-pit mine with a recovery process using cyanide heap leaching followed by carbon adsorption/stripping and electrowinning to produce gold/silver doré bars.

  • Pre-tax cash flows: $494 million non-discounted; $185 million at a 5% discount rate and $70 million at an 8% discount rate.

  • Pre-tax Internal Rate of Return ("IRR"): 10.5%.

  • Total cash operating cost per tonne: $8.35.

  • Total cash operating cost per oz gold: $745 per oz of gold (with silver as a by-product credit).

  • Initial Capital: $455 million (including $60 million in contingency).

Scoping Study Details

The independent scoping study was overseen by Richard Gowans (P.Eng.) of Micon International Limited of Toronto, Ontario Canada ("Micon"), with SRK Consulting (U.S.) Inc. of Reno, Nevada ("SRK") responsible for the heap leach pad design and R. Mohan Srivastava (P.Geo), responsible for the updated resource estimate.

Detailed results of the scoping study are shown below in Table 1.

Table 1. Converse gold project scoping study (all in US Dollars)

Item Units
Base Case Gold price $ per ounce $1300
Base Case Silver Price $ per ounce $25
Initial Mine life years 13.5
Strip ratio Waste rock : mineralized rock 2.3:1
Average annual gold production ounces/year 160,000
Average annual silver production ounces/year 638,000
Average annual gold Eq. production4 Au Eq ounces/year 173,000
Life-of-mine gold production ounces 2,165,000
Life-of-mine silver production ounces 8,471,000
Life-of-mine gold Eq. production4 Au Eq. ounces 2,328,000
Plant processing rate (~45,000 tpd) tonnes/year 16,556,000
Metallurgical recovery - gold % 60%
Metallurgical recovery - silver % 31%
Initial capital 2 $ millions $455
Total Cash operating cost 3 per tonne processed $8.35
Total Cash operating cost 5 per ounce Au (with Ag credit) $745
Total Cash operating cost inc capital 5 per ounce Au (with Ag credit) $998
Pre-Tax IRR % 10.5%
Pre-Tax Cash Flow (non-discounted)6 $ millions $494
Pre-Tax NPV, 5% discount rate6 $ millions $185
Pre-Tax NPV, 8% discount rate6 $ millions $70
1) This scoping study is preliminary in nature, in that it includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves. There is no certainty that the results of the scoping study will be realized and actual results may vary substantially.
2) Initial Capital includes $60 million in contingency allowance. Costs are based on Q3 2011 estimates and no escalation factors have been applied.
3) Total Cash Operating costs include estimates of refining charges.
4) Gold equivalents ("Au Eq.") for production are estimated using a silver-to-gold ratio of 52:1 calculated by using the base case metal prices.
5) By-product accounting subtracts the revenue generated by silver from the total operating costs to determine the cost per ounce of gold.
6) Cash flow and Net Present values ("NPV") are all shown pre-tax, but include 5% net smelter return ("NSR") royalty due to third parties and refining and transportation charges.
7) Mineral resources that are not mineral reserves and do not have demonstrated economic viability.

Sensitivities to gold and silver prices are shown in Table 2 below.

Table 2. Converse gold project sensitivity analyses (base case in bold)

Gold Price/Silver Price ($/oz)
Category $1,000/
IRR -4.3% 6.0% 10.5% 14.7% 22.5% 29.8% 36.8%
Cash Flow
($ millions)
-171 272 494 715 1,158 1,602 2,045
NPV 5%
($ millions)
-269 33 185 336 639 941 1,244
NPV 8%
($ millions)
-300 -54 70 193 440 687 934


The conceptual mining method for Converse is open-pit with truck haulage delivering to a primary crusher. The average life-of-mine strip ratio is 2.3:1. Mining will be by drill and blast for the bedrock, with the overlying gravels not requiring blasting. 350 tonne-capacity haul trucks (approximately 17), loaded by hydraulic shovels will deliver mined material either to the primary crusher or to the waste dump. Bench height in the open-pit is projected to be 12 meters (40 feet).


The conceptual processing plan for Converse envisages 3-stage crushing to 80% passing 9.5mm and cyanide heap leaching followed by carbon adsorption/stripping, electrowinning and smelting to produce gold/silver doré bars for shipment to a refinery.

Initial metallurgical test results by IMZ were published in a press release on November 29th showing metallurgical recoveries for gold of 79%, 80% and 50% for the three completed column tests. These initial results were used in combination with metallurgical testwork conducted by Metallic Ventures, the previous owner of the project, to estimate the gold recovery of 60% used in the scoping study. Silver recoveries are variable and are approximately 50% of the gold recoveries. The metallurgical test program is ongoing in support of an anticipated feasibility study commencing in 2012.


The results presented above have been estimated on a pre-tax basis. However, the Converse project will be subject to US federal income tax at graduated rates ranging from 0% to 35% or at an alternative minimum tax rate of 20%. It is typical for a mining operation in the US to have an effective tax rate below 30% and, for the base-case, Micon expects the project's effective tax rate to be closer to 20%.

A mining operation in Nevada is not subject to state income tax. However, Nevada imposes a tax on the net proceeds of mining operations (Nevada Net Proceeds of Minerals Tax), which is based on a sliding scale between 2% and 5%, depending on the ratio of net proceeds to gross proceeds achieved by the mining operation during the year.

Mineral Resource Estimate Details

Based on drill results received up to a cut-off date of November 4th, 2011, an updated mineral resource estimate was calculated by R. Mohan Srivastava (P.Geo), an independent consultant. This new estimate is a minor update to the mineral resource estimate announced in a press release dated August 24th, 2011 and now includes the silver content of the Converse deposit, which was not previously reported by IMZ.

The updated resource, as shown in Table 3 and summarized below comprises:

  • Measured and Indicated Resources: 320 Mt at an average grade of 0.50 g/t gold and 3.7 g/t silver containing approximately 5.2 million ounces of gold and 38.0 million ounces of silver.

  • Inferred Resources of 31 Mt at an average grade of 0.51 g/t gold and 3.0 g/t silver containing approximately 0.5 million ounces of gold and 3.0 million ounces of silver.

The resource estimate is reported at a cut-off grade of 0.27 g/t gold. Because the cut-off grade is a factor of operating costs, metallurgical recoveries and gold price, it is possible that a lower or higher cut-off grade could be applied in future resource estimates.

Table 3. Converse gold project - Mineral Resource Estimate at a cut-off grade of 0.27 g/t gold (as of December 19, 2011)

Resource Estimate
Tonnes Gold Grade (g/t) Silver Grade (g/t) Contained Ounces
Gold Silver Gold Equivalent
Measured 221,172,000 0.51 3.91 3,590,000 27,828,000 3,868,000
Indicated 99,057,000 0.50 3.18 1,582,000 10,125,000
Measured and Indicated 320,229,000 0.50 3.69 5,172,000 37,953,000 5,551,000
Inferred 31,242,000 0.51 3.00 507,000 3,013,000 537,000
1) Numbers are rounded to reflect the precision of a resource estimate.
2) The estimated mineral resources are not mineral reserves and do not have demonstrated economic viability.
3) Gold equivalent ounces are estimated for mineral resources using 100:1 silver to gold ratio that assumes base case metal prices of $1,300 and $25 for gold and silver respectively and metallurgical recoveries of 60% for gold and 31% for silver.
4) To limit the influence of individual high-grade samples, grade cutting was used. Gold assay grades were capped at 15 g/t and silver grades were capped at 100 g/t.
5) Average dry bulk densities of 2.72 tonnes per cubic meter were used for all mineralized rocks.
6) The grades were interpolated using the "Ordinary Kriging" estimation technique.
7) Descriptions of parameters to determine "Measured", "Indicated" and "Inferred" resources are provided below.
8) The contained metal estimates remain subject to factors such as mining dilution and losses and, process recovery losses.
9) The mineral resources in this press release were estimated using the Canadian Institute of Mining, Metallurgy and Petroleum (CIM), CIM Standards on Mineral Resources and Reserves, Definitions and Guidelines prepared by the CIM Standing Committee on Reserve Definitions and adopted by CIM Council December 11, 2005.
10) IMZ is not aware of any known environmental, permitting, legal, title, taxation, socio-economic, marketing, political, or other relevant factors that could materially affect the validity of these resource estimates.

To date a total of 316 resource definition and other exploration drill holes (both reverse circulation and core) have been completed totaling approximately 65,000m. The current mineral resource estimate is based on the results of 209 drill holes totaling approximately 50,600m, which have defined an area of mineralization over 1,500m by 2,000m. The remaining 107 drill holes are exploration holes that are not close enough to the mineralized body to influence the mineral resource estimation process.

Resource Estimation Methodology

Mineral resources were estimated by the ordinary kriging estimation method using a search ellipse with a radius of 150m by 150m by 50m. The two longer axes of the ellipse were oriented vertically and parallel to the contact with the central intrusive and the short axis was oriented perpendicular to the contact with the intrusive. Converse comprises two deposits -- North and South Redline -- which envelop (wrap around) this central intrusive.

The search ellipse was sub-divided into octants (eight sectors) and within each octant a maximum of four sample assay values were used. The variogram model used for ordinary kriging had ranges of correlation equal to the radiuses of the search ellipse and its orientation was aligned with the search ellipse, with the direction of maximum continuity parallel to the contact with the central intrusive. The estimation using a locally-varying direction of maximum continuity was performed using the consultant's in-house software.

Resource classification was based on three criteria: 1) Distance to the nearest sample, 2) Number of octants with data, and 3) Number of different drill holes. Below are the principal criteria for each resource category:

  • Measured Resources have (a) a sample within one-third of the variogram range, (b) samples from at least four octants, and (c) samples from at least two drill holes.
  • Indicated Resources have (a) a sample within two-thirds of the variogram range, and (b) have samples that came from at least four octants, and (c) samples from at least two drill holes.
  • Inferred resources have (a) a sample within two-thirds of the range of the variogram, (b) no restriction on the number on the minimum number of octants and (c) samples from at least two drill holes.


The technical information reported in this news release was reviewed by IMZ's Qualified Person, VP Corporate Development, Nick Appleyard.

A NI 43-101 compliant Technical Report will be filed by IMZ on SEDAR within 45 days of the date of this news release.

About International Minerals

International Minerals is a silver-gold producer, explorer and developer with silver-gold production from its 40%-owned Pallancata Mine in Peru, which is operated by Hochschild and is one of the top-5 primary silver mines in the world. Production at Pallancata in calendar year 2010 was 10.1 million ounces of silver and 36,000 ounces of gold (on a 100% project basis).

In addition to the Pallancata Mine and a 40% interest in the development stage Inmaculada gold-silver project, IMZ also owns a 100% ownership interests in advanced stage gold projects in Nevada (Goldfield and Converse) and variable interests in gold projects in Ecuador (Rio Blanco 100% and Gaby 60%).

IMZ also holds a 3% NSR royalty from Barrick Gold Corporation's Ruby Hill gold mine in Nevada, which produced approximately 80,000 gold ounces in 2010.

IMZ is listed on the Toronto Stock Exchange (since 1994) and the Swiss Stock Exchange (since 2002).

Cautionary Statement:
Some of the statements contained in this release are "forward-looking statements" within the meaning of Canadian securities law requirements. Such forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to differ materially from the anticipated results, performance or achievements expressed or implied by such forward-looking statements. Forward-looking statements in this release include statements regarding estimates of capital and operating costs; economic returns; timing and significance of future cash flows and revenue from the project; timing and outcome of any feasibility study; and timing and scale of production and processing; and resource estimates. Factors that could cause actual results to differ materially from anticipated results include risks and uncertainties such as: risks relating to estimates of production and processing rates; risks relating to estimates of mineral resources; risks relating to capital and operating costs; risks relating to obtaining mining and environmental permits; mining and development risks; risk of commodity price fluctuations; political and regulatory risks; and other risks and uncertainties detailed in the Company's Renewal Annual Information Form for the year ended June 30, 2011, which is available at under the Company's name.

A number of measures reported above are non-IFRS (International Financial Reporting Standards) financial measures which include: total cash operating costs per tonne; total cash operating costs per ounce (with by-product credit): and total cash operating costs per ounce (with by-product and including capital). Management believes these items may be useful measures to analyze the economics of the Converse project, but readers of this news release should not rely on these non-IFRS measures in isolation.

The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Contact Information

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    Vice President Corporate Relations
    Tel: +1 203 883 8359

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    Marketing Consultant
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