Mindoro Resources Ltd.

Mindoro Resources Ltd.

March 21, 2007 09:00 ET

Mindoro Resources Ltd.: Excellent Metallurgical Test Results From Kay Tanda

EDMONTON, ALBERTA--(CCNMatthews - March 21, 2007) - Mindoro Resources Ltd. (TSX VENTURE:MIO)(FRANKFURT:WKN 906167) today reported that high gold recoveries were obtained in a third round of metallurgical tests of large diameter drill core composites from both oxide and mixed (transitional) oxide and sulphide mineralized material from the Kay Tanda gold-silver prospect, Philippines. The results to date indicate that both composites are highly amenable to heap leaching. It appears that most of the gold occurs in the cracks and fissures in the rocks and is readily accessible to the cyanide solution. Gold dissolution is rapid and high gold recoveries have been obtained from both composites, and with low cyanide consumption.

Kay Tanda is being evaluated for its open-pit, heap-leach potential. Preliminary bottle roll metallurgical test work on reverse circulation cuttings was largely positive (reported on January 14, 2004). A second round of testing was carried out on a small bulk sample of oxidized mineralized material from a pit and gave excellent results (reported on December 2, 2005). The current test had the objective of evaluating heap leach characteristics of near-surface oxide mineralization, as well as deeper mixed oxide/sulphide (transition) mineralization. Samples were collected by large diameter (PQ) core drilling and submitted to Metcon Laboratories, in Australia. The program was designed and supervised by an independent consultant, Peter J. Lewis and Associates of Australia.

Two series of testwork were completed on the two composites. The first test was a bottle roll test on composites at 80% passing a sieve at 75um. This test is required to indicate the maximum gold and silver recoveries obtainable and to compare these with the recoveries obtained by heap leach testing. Very high gold and silver recoveries were obtained from both types of mineralized material. From the oxide material 93.4% of the contained gold and 83.7% of the contained silver was leached and recovered in 48 hours. From the transition material (mixed oxide and sulphides) 88.6% of the gold and 87% of the contained silver was leached. These are unusually high recoveries, especially for the sulphide-containing material.

For the second round of testing, column tests (heap leach tests) were performed on a crush size of minus 12.7mm, i.e. 1/2 inch, which is close to the lower size limit normally used for heap leaching. Gold recovery from the oxide material after 29 days of leaching was 80.3%. Gold recovery from the transition material after 23 days was 80.6%. Silver recoveries are awaited. Both composites are highly amenable to heap leaching.

Because of the encouraging results a further test was commenced at a very coarse crush size of 50mm (2 inches), since the coarser the crush, the lower the processing costs. This work is in progress, and results will be reported on completion. Since the transition sample contained a high proportion of sulphide-related mineralization, and leached very well, a test will also be carried out on deeper, entirely sulphide-related gold and silver mineralization as well.

Mindoro management is most encouraged by the results from Kay Tanda to date and considers them a strong basis for further evaluation of the project's economic potential. Preliminary work on a National Instrument 43-101 resource estimate has commenced, to be followed by a scoping study.

The program is carried out under the supervision of J. A. Climie, P. Geol., President of Mindoro and a "qualified person" as defined by National Policy 43-101. Metallurgical reports will be posted on Mindoro's website on completion of all testwork.


Low sulphidation epithermal gold-silver mineralization at Kay Tanda is associated with extensive and intense hydrothermal breccias, quartz stockworks, with accompanying base metal sulphides, and emplaced in to an area of strong advanced argillic alteration. It is reflected by an induced polarization chargeability anomaly that is about 1.5 kilometers by 1.4 kilometers in extent. Less than 25% of the chargeability anomaly has been drill-tested to date. The latter is interpreted as part of a much larger mineral system consisting of epithermal gold-silver and base-metal mineralization telescoped into an underlying porphyry copper-gold system.

Mindoro has completed over 120 reverse circulation (RC) and nine core drill holes at Kay Tanda. Almost all holes have encountered near-surface, generally flat-lying to gently-dipping blanket-like low-grade mineralization, which is partially to strongly oxidized to depths of 40 to 60 meters and non-oxide (sulphide) below this. Drilling, especially at deeper levels, has encountered at least four steeper-dipping and much higher-grade zones, with bonanza grades to 100 g/t gold and over 1,000 g/t silver, in places, which are interpreted as structurally controlled upflow, or "feeder" zones. Further drilling and structural studies are in progress to determine the nature and controls of the high-grade zones. Mineralization is thought to be related to swarms of hydrothermal breccias, and prospect-scale quartz stockworking, with the high-grade occurring preferentially at elevations below 150 meters (ASL) within a boiling zone. Few holes have penetrated to this depth to date. Such upflow zones can be associated with bonanza mineralization and constitute some of the world's best epithermal gold-silver deposits.


Mindoro is a Tier 1 Issuer trading on the TSX Venture Exchange (MIO) and the Frankfurt Stock Exchange (WKN 906167). In addition to the resource delineation being carried out at Kay Tanda, the company has identified 22 porphyry copper-gold prospects and a significant nickel laterite prospect in the Philippines and has an aggressive strategy of drilling multiple targets in 2007.

This release may contain forward-looking statements including management's assessments of future plans and operations, and expectations of future production. These statements are based on current expectations that involve a number of risks and uncertainties, which could cause actual results to differ materially from those anticipated. These risks include, but are not limited to, the risks associated with the mining and exploration industry (e.g. operational risks in development, exploration and production; delays or changes in plans with respect to exploration or development projects or capital expenditures; the uncertainty of reserve estimates; the uncertainty of estimates and projections relating to production). The assumptions used in the preparation of such statements, although considered reasonable at the time of preparation, may prove to be imprecise and, as such, undue reliance should not be placed on forward-looking statements.

The TSX Venture Exchange has not reviewed and does not accept responsibility for the adequacy or accuracy of this release.

Contact Information

  • Mindoro Resources Ltd. - Head Office
    Penny Gould
    Executive Vice President
    (780) 413-8187
    Email: penny@mindoro.com
    Website: www.mindoro.com
    Ascenta Capital Partners Inc.
    Trent Dahl
    Investor Relations - Canada
    (604) 628-5800 or Toll Free: 1-866-684-4209 ext. 228
    Email: info@mindoro.com
    Argentuminvest GmbH
    Richard Mayr
    Investor Relations - Europe
    +49.9421.785255 (FAX)
    Email: info@argentuminvest.com