International Minerals Increases Gold Resource Estimate at Goldfield Project, Nevada; Additional Drill Results Include 39.6m at 2.4 g/t Gold
SCOTTSDALE, AZ -- (Marketwire) -- 02/01/11 -- International Minerals Corporation (TSX: IMZ) (SWISS: IMZ) reports an updated, increased mineral resource estimate for the Goldfield Main deposit at the 100%-owned Goldfield gold project in central Nevada. It is IMZ's first resource estimate update at the Goldfield project since IMZ's acquisition of the project by acquiring Metallic Ventures Gold Inc ('MVG') in February 2010.
The Goldfield Main deposit is only one of three principal mineralized areas that have been evaluated on the Goldfield property over the past two decades. The other deposits are Gemfield and McMahon Ridge. Goldfield Main was the site of significant historical underground mining operations that reportedly produced roughly four million ounces of gold in the early 1900s.
Below is the updated resource estimate for Goldfield Main using a 0.4 grams/tonne (g/t) cut-off grade.
Indicated Resources: 421,000 ounces ('ozs') of gold contained within 8.5 million tonnes ('mt') at an average grade of 1.5 g/t gold. This represents a 74% increase in estimated gold resource ounces compared to the previous Goldfield Main indicated resource estimate and a 17% increase in total measured and indicated resources for the overall Goldfield project.
Inferred Resources: 360,000 ozs of gold contained within 6.6 mt at an average grade of 1.7 g/t gold. This represents a 348% increase in estimated gold resource ounces compared to the previous Goldfield Main inferred resource estimate and a 265% increase in total inferred resources for the overall Goldfield project. (Note: the high percentage change in the inferred resources is due to the modest amount of the previous resource estimate that was classified in the inferred category).
IMZ is confident that its ongoing drilling program, in areas to the east not previously drilled, will further increase the mineral resources at Goldfield Main.
Table 1: Goldfield project, Goldfield Main - Mineral Resource Estimate - February 1st, 2011
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Resource Estimate Cut-Off Gold Grade
Category (g/t gold) Tonnes (g/t) Gold Ounces
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Indicated 0.6 7,053,000 1.8 397,000
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0.5 7,829,000 1.6 410,000
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0.4 8,549,000 1.5 421,000
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0.3 9,163,000 1.5 427,000
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Inferred 0.6 5,446,000 2.0 343,000
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0.5 5,979,000 1.8 352,000
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0.4 6,591,000 1.7 360,000
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0.3 7,073,000 1.6 367,000
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1. Gold price used for the estimate is US$1,200/oz.
2. The estimated resources are reported at a 0.4 g/t gold cut-off grade,
which corresponds to an assumed $10 per tonne marginal cash operating
cost. This case is shown in bold text in the Table above.
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 with Micromine software using
ordinary kriging to estimate metal grades.
Outlier high-grade assay were top-cut, using values that depended on lithology and location. Inside the main mineralized structure, assays in intervals with lithologies that often have high gold grades were capped at 75 g/t, and assays in intervals with lithologies that rarely have high gold grades were capped at 7.5 g/t. Outside the main mineralized structure, the corresponding capping values were 9 g/t (for high-grade lithologies) and 5 g/t (for low-grade lithologies).
The Goldfield Main mineral resource estimate has been classified in accordance with CIM guidelines by independent consultant R. Mohan Srivastava (P.Geo), a Qualified Person under NI 43-101. The estimate has an effective date of February 1st, 2011.
The mineral resource estimate is based on the results of 1,116 drill holes totaling approximately 110,000m, (up to and including the drill holes shown in Appendix 1), which have defined an area of mineralization of over 450m by 1,200m, with an approximate 30 degree dip to the east. The main mineralized zone, which is still open down dip to the east, has been intersected by more than 800 drill holes, and contains more than 12,000 assays from approximately 18,000m of drilling.
The previous resource estimate, published in September of 2002 by MVG, was calculated for MVG by Qualified Person ('QP') S. Ristorcelli of Mine Development Associates of Reno, Nevada. It was reported at a cut-off of 0.27 g/t gold and comprised indicated resources of 241,800 ozs gold contained within 6.0 mt at an average grade of 1.2 g/t gold and inferred resources of 80,300 ozs gold contained within 1.9 mt at an average grade of 1.3 g/t gold.
Resource Estimation Methodology
The resource estimation was constrained using a wireframe model to outline an east-dipping alteration ('EDA') mineralized zone. The wireframe was constructed from cross-sectional interpretation of the EDA at Goldfield Main by IMZ geologists. A search ellipse with radii of 42.7m and 30.5m (in the plane of the EDA) and 6.1m perpendicular to the EDA sub-divided into octants, was then used to interpolate grades into the 6.1m by 6.1m by 3.0m blocks using the Ordinary Kriging capability of Micromine software. Length-weighting was used to adjust for unequal sample length intervals. Tonnage factors were assigned using block-by-block estimates of the proportion of in-situ rock (2.14 tonnes per cubic meter ('t/m3')), back-filled stopes (1.53 t/m3) and voids from historical mining.
Within the EDA, mineral resources were classified as Indicated for all blocks that met the following criteria: 1) at least one sample within half the range of the variogram; 2) at least four samples from two different drill holes in three octants. Blocks that did not meet these criteria were classified as Inferred.
Additional Drill Hole Results at Goldfield Main
IMZ also reports additional results from its ongoing reverse circulation ('RC') drilling program at the Goldfield Main deposit.
Highlights from this drilling program (representing estimated true widths in meters and uncut gold grades in g/t), include the following intercepts:
- 4.3m at 3.4 g/t in 2010-008
- 2.7m at 4.4 g/t in 2010-008
- 6.1m at 2.2 g/t in 2010-009
- 32.0m at 1.3 g/t in 2010-089
- 6.1m at 8.4 g/t in 2010-108
- 18.3m at 4.2 g/t in 2010-111
- 39.6m at 2.4 g/t in 2010-112
Note: Some of the above highlighted drill intersections include zones of low-to-average grade material from backfill material used in historical mine workings, but are predominantly in-situ mineralization.
Assay results for all 35 RC drill holes totaling 9,025m are summarized in Appendix 1 and shown on the plan map in Appendix 2 (Click here for news release with full appendices - http://www.intlminerals.com/newsreleases.php) . IMZ has now reported drill results for a total of 121 RC drill holes totaling 26,600m.
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, one of the top-10 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, IMZ also owns a 40% interest in the Inmaculada gold-silver project in Peru and majority or 100% ownership interests in development stage gold projects in Nevada (Goldfield and Converse) and Ecuador (Rio Blanco and Gaby). IMZ also holds a 3% net smelter return ('NSR') 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. Factors that could cause actual results to differ materially from anticipated results include risks and uncertainties such as: risks of estimating mineral resources 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.
Appendix 1: Goldfield Project - Goldfield Main Drill Results
IMZ News Release dated February 1, 2011
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Inter-
Drill Section Total section Host Intercept Intercept True Gold
Hole Number Type Depth From-To Rock (feet) (meters) Width (g/t)
(feet) (feet) (meters)
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2010-
007 10400 Extension 600 455-530 Rock 75 22.9 22.9 0.9
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2010-
008 10500 Extension 600 115-130 Rock 15 4.6 4.3 3.4
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130-135 Void -- -- -- --
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135-150 Rock 15 4.6 4.3 0.5
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Stope
150-170 Fill 20 6.1 5.5 0.6
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170-180 Rock 10 3.0 2.7 4.4
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Stope
180-185 Fill 5 1.5 1.4 0.3
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270-285 Rock 15 4.6 4.3 1.6
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340-355 Rock 15 4.6 4.3 0.7
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420-480 Rock 60 18.3 16.8 0.7
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2010-
009 10500 Extension 840 195-225 Rock 30 9.2 Unknown 3.4
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675-700 Rock 25 7.6 6.1 2.2
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2010-
013 10700 Extension 720 425-540 Rock 115 35.1 35.1 0.7
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2010-
089 12100 Extension 740 500-605 Rock 105 32.0 32.0 1.3
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2010-
090 12300 Extension 740 670-715 Rock 45 13.7 13.7 0.6
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2010-
091 12300 Extension 670 590-660 Rock 70 21.3 18.3 1.0
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2010-
094 11600 Extension 860 675-730 Rock 55 16.8 16.8 0.8
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2010-
095 12300 Extension 900 No Significant Values
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2010-
096 12300 Extension 1,000 745-790 Rock 45 13.7 13.7 0.5
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2010-
097 12100 Extension 750 615-630 Rock 15 4.6 4.6 0.7
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2010-
098 12100 Extension 850 No Significant Values
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2010-
099 12100 Extension 980 35-50 Rock 15 4.6 Unknown 0.6
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745-760 Rock 15 4.6 4.6 0.8
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2010-
100 11900 Extension 720 No Significant Values
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2010-
101 11900 Extension 850 670-735 Rock 65 19.8 18.9 0.7
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2010-
102 11900 Extension 950 65-75 Rock 10 3.0 Unknown 0.7
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2010-
103 11700 Extension 800 670-685 Rock 15 4.6 4.6 1.3
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2010-
104 11700 Extension 850 755-765 Rock 10 3.0 3.0 0.7
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2010-
105 11700 Extension 900 760-800 Rock 40 12.2 12.2 0.8
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2010-
106 11500 Extension 820 735-775 Rock 40 12.2 10.7 1.0
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2010-
107 11500 Extension 915 No Significant Values
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2010-
108 11500 Extension 900 130-150 Rock 20 6.1 Unknown 8.4
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800-875 Rock 75 22.9 22.9 0.8
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2010-
109 11300 Extension 700 Failed to Reach Target Depth
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2010-
110 11300 Extension 950 845-855 Rock 10 3.0 3.0 0.5
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2010-
111 11100 Extension 780 710-780 Rock 70 21.3 18.3 4.2
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2010-
112 11100 Extension 860 730-860 Rock 130 39.6 39.6 2.4
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2010-
113 11100 Extension 1,020 820-875 Rock 55 16.8 16.8 0.8
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2010-
114 10900 Extension 880 185-190 Rock 5 1.5 Unknown 1.3
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610-625 Rock 15 4.6 4.6 1.5
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2010-
115 10900 Extension 990 275-280 Rock 5 1.5 Unknown 1.2
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2010-
116 11300 Extension 960 825-835 Rock 10 3.0 3.0 0.7
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2010-
117 11500 Extension 635 Failed to Reach Target Depth
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2010-
118 11100 Extension 1,080 No Significant Values
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2010-
119 11300 Extension 785 Failed to Reach Target Depth
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2010-
120 11100 Extension 1,090 No Significant Values
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2010-
121 11100 Extension 925 915-925 Rock 10 3.0 Unknown 1.0
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Note: 'Void' indicates zone where old mine workings were intersected in the drill hole and therefore no sample was recovered. 'Stope Fill' is where old mine workings were intersected and mine back fill was recovered and sampled.
'Unknown' indicates zones where true widths of mineralization could not be determined.
Core drilling will be used to confirm the presence and continuity of historical Stope Fill, which can at times be difficult to identify from RC chips.
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Tel: 1 203 940 2538
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Internet Site: http://www.intlminerals.com