International Minerals Reports Increased Resource Estimate at Converse Gold Project in Nevada 5.1 Million Gold Ounces in Measured and Indicated Resources
5.1 Million Gold Ounces in Measured and Indicated Resources
SCOTTSDALE, AZ -- (Marketwire) -- 08/24/11 -- International Minerals Corporation (TSX: IMZ) (SWISS: IMZ) reports an updated, increased mineral resource estimate for the 100%-owned Converse gold project. Converse is located in the prolific Battle Mountain-Cortez mineralized trend in north-central Nevada, approximately 8km west of Goldcorp's Marigold gold mine.
IMZ anticipates completing a Preliminary Economic Assessment (Scoping Study) on the Converse project by the end of 2011.
Below is the updated resource estimate for Converse using a 0.27 grams/tonne ('g/t') gold cut-off grade.
Measured and Indicated Resources: 5.146 million ounces ('ozs') of gold contained within 331 million tonnes at an average grade of 0.48 g/t gold, comprising:
Measured Resource: 3.515 million ozs of gold contained within 225 million tonnes at an average grade of 0.49 g/t gold.
Indicated Resource: 1.632 million ozs of gold contained within 106 million tonnes at an average grade of 0.48 g/t gold.
Inferred Resource: 0.444 million ozs of gold contained within 32 million tonnes at an average grade of 0.44 g/t gold.
Compared to the prior resource estimate announced in September 2004 by the previous owners of Converse, Metallic Ventures Gold Inc., ('Metallic') at a similar cut-off grade (0.008 oz/ton in imperial measurements), IMZ's new resource estimate represents a 27% increase in contained gold ounces with a minor (3%) decrease in gold grade in the Measured and Indicated resource categories and a small decrease (56,000 gold ounces) in the Inferred resource category.
Details of the resource estimates at various cut-off grades are shown in Table 1 below (base case bolded).
Table 1: Converse Project - Mineral Resource Estimate - August 24, 2011
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Gold
Resource Estimate Cut-Off Gold Grade Ounces
Category (g/t gold) Tonnes (g/t) (millions)
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Measured 0.40 129,324,000 0.61 2.521
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0.27 224,642,000 0.49 3.515
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0.20 300,839,000 0.42 4.076
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Indicated 0.40 52,772,000 0.64 1.087
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0.27 106,270,000 0.48 1.632
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0.20 180,072,000 0.37 2.169
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Measured and
Indicated 0.40 182,096,000 0.62 3.608
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0.27 330,912,000 0.48 5.146
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0.20 480,991,000 0.40 6.245
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Inferred 0.40 12,677,000 0.61 0.247
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0.27 31,677,000 0.44 0.444
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0.20 46,558,000 0.37 0.553
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1. The cut-off grade for the base case estimate assumes a metal price of
US$1,200/oz for gold, with an assumed metallurgical recovery in the
range of 50% to 60%.
2. An overall average bulk density for bedrock of 2.72 tonnes per cubic
metre has been used for the tonnage estimation.
3. The estimated mineral resources are not mineral reserves and do not have
demonstrated economic viability.
4. Numbers have been rounded in all categories to reflect the precision of
the estimates.
5. The mineral resources were estimated using ordinary kriging to estimate
metal grades. A block size of 15.2 meters ('m') by 15.2 m by 6.1 m in
size (50 feet by 50 feet by 20 feet) was used and outlier high grades
were top-cut to 15 g/t gold.
IMZ President and CEO, Steve Kay, stated 'Reaching 5 million gold ounces in the Measured and Indicated resource category is a significant milestone that validates the great potential of the Converse deposit that IMZ saw when we acquired Metallic in 2010. In addition, the results so far from the deep drilling completed below the base of historical drilling shows strong potential to significantly increase the size of the deposit in the future. With continuing high gold prices, IMZ management is convinced that Converse is on its way to becoming another significant gold mine in this well-known mineralized trend in Nevada.'
The Converse mineral resource estimate has been classified in accordance with CIM guidelines by independent consultant R. Mohan Srivastava (P.Geo), a Qualified Person ('QP') under NI 43-101. The estimate has an effective date of August 24, 2011.
To date a total of 314 resource definition and other exploration drill holes (both reverse circulation and core) have been completed totaling approximately 64,000m. The current mineral resource estimate is based on the results of 207 drill holes totaling approximately 49,500m, which have defined an area of mineralization over 1,500m by 2,000m.
IMZ recently announced (see IMZ press release dated July 5th, 2011) assay results from two core holes at Converse that were drilled to approximately 550m below surface. These deep drill holes indicate that gold mineralization continues at depth below the previously-tested base of drilling (350m) and together with the resource estimation method described below contributed to the significant increase in Measured and Indicated resources in the current resource estimate.
IMZ is presently completing a further four deep drill holes (to at least 550m below surface), which will allow for greater confidence in the future estimation and resource classification of the deep mineralization and may also increase the overall mineral resource at the Converse project.
IMZ is currently carrying out metallurgical testwork (column leaching) at McClelland's Lab in Sparks, Nevada to further evaluate the planned heap leach recovery process and to validate the previous metallurgical testwork carried out by Metallic.
Resource Estimation Methodology
Mineral resources were estimated by the ordinary kriging estimation method. The kriging program used a search ellipse with a radius of 150m by 150m by 50m, with the two longer axes of the ellipse oriented vertically and parallel to the contact with the generally unmineralized central intrusive and the short axis oriented perpendicular to the contact with the intrusive. Converse comprises two deposits (named 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 radii 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 resource estimation, using a locally-varying direction of maximum continuity, was performed using 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) 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.
Below the base of the previous Metallic drilling, where IMZ's new drill holes reach considerably deeper than the previous drilling, no mineral resource estimates were calculated for blocks that had data from only one nearby drill hole or that had no data within two-thirds of the range of the variogram.
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 approximately 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 (also in Peru and scheduled to commence production in late 2013), IMZ also has 100% ownership interests in development stage gold projects in Nevada (Goldfield and Converse) and variable interests in development stage gold projects in Ecuador (Rio Blanco 100% and Gaby 60%).
IMZ also holds a 3% net smelter return royalty from Barrick Gold'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). The technical information reported in this news release was reviewed by IMZ's Qualified Person, VP Corporate Development, Nick Appleyard.
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 mineral resource estimates and planned economic studies. Factors that could cause actual results to differ materially from anticipated results include risks and uncertainties such as: risks of estimating mineral resources, risks of completing economic studies, including variations in metals prices and operating and capital costs and other risks and uncertainties detailed in the Company's Renewal Annual Information Form for the year ended June 30, 2010, which is available at www.sedar.com under the Company's name. 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.
To access this news release from IMZ's website, please click this link: http://www.intlminerals.com/newsreleases.php.
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