Maiden Porphyry Copper-Gold Resource Estimate 500 Million Tonnes at 0.4% Copper, 0.5g/t Gold
This Delivers 2.1Million Tonnes of Contained Copper and 8 M Ounces of Contained Gold at A 0.2% Cu Cutoff.Maiden Inferred Resource Open Laterally and at Depth.
Drilling Continues With 5 Rigs.
BRISBANE, AUSTRALIA -- (Marketwire) -- 09/29/10 -- Intrepid Mines Limited (TSX: IAU)(ASX: IAU) ('Intrepid' or the 'Company') reports that an initial Inferred Resource of 500 million tonnes at 0.4% copper and 0.5 g/t gold, at a cut-off grade of 0.2% copper, has been estimated for the known porphyry copper-gold zone of the Tumpangpitu area of the Tujuh Bukit Project in Indonesia.
The resource estimate is from the area shown in the attached diagram as the 'Tumpangpitu Maiden Porphyry Resource Outline' and covers a roughly circular area, based on the resource block model, of approximately 1,400 metres diameter. The vertical extent of mineralisation defined to date is up to 800 metres.
The estimate is based on 13 deep drill holes and data from the deeper holes designed to test the near-surface oxidised gold and silver zones that also intersected the underlying porphyry zone. The 13 deep holes - GTD 29, 35, 42, 46, 56, 112, 138, 139, 146, 162, 163, 165, and 166 - delivered intersections that are spaced at approximately 200 metre intervals.
Holes 162, 165 and 166 were being drilled and were still in mineralisation at the time of close off for the resource estimate. Data from all completed holes and those portions of the holes that had been returned up to the close off date was used for this estimate. Complete hole assays for holes 162, 165 and 166 will be reported separately once the holes are finished and assays returned. Some data from abandoned holes GTD 156 and 160 also contributed to the estimate.
This initial resource has been estimated by Independent Consultants Hellman and Schofield Pty. Ltd. and reported in accordance with the JORC Code and NI 43-101.
Intrepid is confident that the porphyry copper-gold resource base at Tumpangpitu will continue to grow as additional drilling is completed over the next 6 months. This drilling will comprise additional exploration laterally to the current resource but still within the area shown in the figure below. The system remains open in all directions, and at depth to the NE and SW. The Company's best hole, GTD163, was on the north east margin (589.5 metres at 0.57g/t gold and 0.65% copper). The program will also explore the domain covering in excess of one kilometre to the south east where hole GTD 137 intersected 85.85 metres at 1.11g/t gold and 0.56% copper at approximately 600 metres vertical depth (see release dated 14 April 2010).
The Tumpangpitu copper-gold porphyry is a gold-rich system. The table below titled 'Summary of Inferred Resource Estimates, by copper or gold cut-offs' demonstrates the increased tonnages that may apply at a copper or gold cut-off. For example, it captures domains that may contain less than 0.2% copper but greater than 0.2 grams per tonne gold.
This current resource estimate is in addition to the oxide gold-silver zone of 95.3 million tonnes at 0.66g/t gold and 25.9 g/t silver for 2 Mozs contained gold and 79.4 Mozs contained silver (see release dated 25 August 2010), and which is also continuing to grow with ongoing drilling.
CEO Brad Gordon said: 'This inaugural porphyry resource estimate firmly identifies Tujuh Bukit as potentially a world-class copper-gold project. It has already delivered beyond our expectations and we look forward to continuing to extend the as yet undefined boundaries of this system. It's still early days for us but we are aggressively advancing both the sulphide and oxide components of this exceptional project and, with US$40 million in the bank, we remain well funded.'
Summary of Inferred Resource Estimates, by Copper (Cu) Cut-offs
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Cut-off M Tonnes Cu (%) Au (g/t) Mo (ppm)
(Cu %)
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0.2 500 0.4 0.5 80
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0.3 350 0.5 0.6 100
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0.4 200 0.6 0.7 130
--------------------------------------------------------------
0.5 150 0.7 0.8 150
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(figures in this and subsequent tables are rounded)
Summary of Inferred Resource Estimates, by Gold cut-offs
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Cut-off M Tonnes Cu (%) Au (g/t) Mo (ppm)
(gold g/t)
--------------------------------------------------------------
0.2 500 0.4 0.5 80
--------------------------------------------------------------
0.3 350 0.5 0.6 100
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0.4 250 0.5 0.7 110
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0.5 200 0.6 0.8 120
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Summary of Inferred Resource Estimates, by Copper or Gold cut-offs
--------------------------------------------------------------
Cut-off M Tonnes Cu (%) Au (g/t) Mo (ppm)
(Au g/t or
Cu %)
--------------------------------------------------------------
0.2 600 0.4 0.4 80
--------------------------------------------------------------
0.3 400 0.5 0.6 90
--------------------------------------------------------------
0.4 300 0.5 0.7 100
--------------------------------------------------------------
0.5 200 0.6 0.7 120
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To view Figure 1, please visit the following link: http://media3.marketwire.com/docs/IAU929fig1.pdf
To view Figure 2, please visit the following link: http://media3.marketwire.com/docs/IAU929fig2.pdf
Forward-looking statements
This announcement contains certain forward-looking statements, relating to, but not limited to Intrepid's expectations, intentions, plans and beliefs. Forward-looking information can often be identified by forward-looking words such as 'anticipate', 'believe', 'expect', 'goal', 'plan', 'intend', 'estimate', 'may' and 'will' or similar words suggesting future outcomes, or other expectations, beliefs, plans, objectives, assumptions, intentions or statements about future outcomes, or statements about future events or performance. Forward-looking information may include reserve and resource estimates, estimates of future production, unit costs, costs of capital projects, and timing of commencement of operations and is based on current expectations that involve a number of business risks and uncertainties. Factors that could cause actual results to differ materially from any forward-looking statement include, but are not limited to, failure to establish estimated resources and reserves, the grade and recovery of ore which is mined varying from estimates, capital and operating costs varying significantly from estimates, delays in obtaining or failures to obtain required governmental, environmental or other project approvals, inflation, changes in exchange rates, fluctuations in commodity prices, delays in the development of projects and other factors. Forward-looking statements are subject to a variety of known and unknown risks, uncertainties and other factors that could cause actual events or results to differ materially from those expressed or implied.
Shareholders and potential investors are cautioned not to place undue reliance on forward-looking information. By its nature, forward-looking information involves numerous assumptions, inherent risks and uncertainties, both general and specific, that contribute to the possibility that the predictions, forecasts, projections and various future events will not occur. Intrepid undertakes no obligation to update publicly or otherwise revise any forward-looking information whether as a result of new information, future events or other such factors which affect this information, except as required by law.
Statements relating to gold resource estimates are expressions of judgment, based on knowledge and experience and may require revision based on actual production experience. Such estimates are necessarily imprecise and depend to some extent on statistical inferences and other assumptions, such as gold prices, cut-off grades and operating costs, which may prove to be inaccurate.
Forestry Activities
The Indonesian Forestry Law restricts non forestry activities within protected forests and prohibits mining using an open pit method in protected forest areas. The area of the Porphyry copper-gold resource estimate, and the Zone A, Zone B and Zone C oxide resource estimate areas fall within a protected forest area. Intrepid's Alliance partner, PT IMN, is working with relevant Indonesian authorities regarding a potential review of forest land status. While similar reviews have led to the granting of reclassifications, there is no assurance that the forestry reclassification will take place in this instance. PT IMN received an extension of the Forestry Exploration Permit dated 7 July 2010, which allows for exploration activities within forestry areas.
Qualified Person
The information in this announcement that relates to exploration results is based on information compiled by or under the supervision of Malcolm Norris, who is a full-time employee of Intrepid Mines Limited. Mr. Norris has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2004 Edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves' and a Qualified Person as defined in the Canadian National Instrument 43-101 (standards of Disclosure for Mineral Projects). Mr. Norris consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.
The information in this announcement that relates to mineral resources is based on information compiled by or under the supervision of Dr. Phillip Hellman, who is an independent consultant to Intrepid Mines Limited. Dr Hellman has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as an Independent Competent Person as defined in the 2004 Edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves' and an Independent Qualified Person as defined in the Canadian National Instrument 43-101 (standards of Disclosure for Mineral Projects). Dr Hellman consents to the inclusion in the report of the matters based on his information in the form and context in which it appears. Dr Hellman has undertaken independent verification sampling and assaying of drill core with a close agreement of results with those previously reported. A 40 x 40 x 15 metre block model was used for the quoted estimates.
Resource Estimation Notes
Geological interpretations of the copper mineralisation provided by Intrepid were used to define a 'top-of-porphyry' surface to restrict estimates to geologically reasonable limits. The block model was coded by oxidation zone and estimates were restricted to the sulphide or transitional zones as well as to the potential porphyry zone. 6m length-weighted composites from the transitional and sulphide zones were used to estimate, via Ordinary Kriging, Cu, Au, Mo, As, SG and Ag into a 40 x 40 x 15 metre block model. Silver values within the primary mineralisation are low (eg less than 5g/t) and their estimates are not reported.
Inferred Resources are defined on the basis of a 120m x 120m x 80m search ellipsoid using a maximum of 32 6m composites and a minimum of 12. Two more passes to 240m x 240m x 160m were used to generate 'potential' blocks within the constraints of the porphyry model. In general, these potential blocks define extra similar tonnages at similar grades to the quoted estimates. These, however, do not constitute 'resource estimates' and there is no guarantee that they will be upgraded to resources with further drilling. Drill spacing of the deeper holes is approximately 200m x 200m. However, there are a considerable number of shallower holes that intersected copper mineralisation in transitional and primary mineralisation. Approximately 5% of quoted resources are from transitional mineralisation. 5172 6m composites of Cu and Au are available for estimation together with 5072 Mo, 4955 As and 3446 SG values. Composites from the porphyry zone number 2408, 2408, 2379, 2402 and 1684 for Cu, Au, Mo, As & SG, respectively.
Two different software products were used to provide estimates as well as two different operators. Results closely agree within the meaning of 'Inferred'. Cross sections of the modelled results were plotted in juxtaposition with assay and geological data to check for geological plausibility. It is noted that there is considerable scope to add to the quoted resource with most sections having significant areas that are yet to be drill tested.
Due to the preliminary nature of the project, pit optimisation has not yet been undertaken resulting in uncertainty as to how much of the resource may report to a conceptual pit. At a 0.2% Cu cut off grade the following tonnages occur at greater than 0m elevation, 0 to -200m, -200m to -400m and -400m to -600m: 58mt, 131mt, 196mt and 114mt respectively. Although these depths preclude open pit mining in the deeper portions of the resource, the possibility of bulk underground mining techniques (eg block caving) remains.
Sample Analysis
Intrepid exercises a strict chain of sample custody in its drilling program at Tujuh Bukit. Joint Venture personnel remove core from the drill rig and deliver it to a project geologist who logs the core and marks the core into two metre sample intervals. Intrepid and Joint Venture personnel supervise the immediate splitting, sawing and bagging of samples, and packaging of groups of samples for dispatch to the laboratory. The remainder of the split core remains on site.
Samples are securely packaged, batched, and then transported under supervision to Intertek's laboratory facility in Jakarta. At the laboratory, the samples are prepared by crushing and pulverizing and a 30 gram charge is assayed for gold by conventional fire assay and/or atomic absorption methods. Multi-element ICP analysis is carried out using a multi-acid digestion process. All samples that contain silver and/or copper, lead, and zinc values that exceed the upper detection limits for ICP are re-analysed by conventional atomic absorption methods to determine the absolute values of these metals.
Contacts:
Intrepid Mines Limited
Brad Gordon
Chief Executive Officer
Brisbane, Australia
+61 7 3007 8011
bgordon@intrepidmines.com
Intrepid Mines Limited
Greg Taylor
Toronto, Canada
+905 337 7673 or Mobile: +416 605 5120
gtaylor@intrepidmines.com
www.intrepidmines.com