Iamgold tallies Quimsacocha (October 28, 2005)

Roscoe Postle Associates has tagged Iamgold‘s (IMG-T IAG-X) still-growing Quimsacocha gold-copper-silver deposit in Azuay province, Ecuador with an initial indicated mineral resource estimate totalling 2.8 million oz.

The ounces are contained in 22.5 million tonnes of ore running 3.9 grams gold and 25 grams silver per tonne, plus 0.16% copper, including a high-grade zone of 8.5 million tonnes averaging 6.8 grams gold, 42 grams silver and 0.24% copper. Another 2.5 million tonnes averaging 2.1 grams gold, 15 grams silver, and 0.12% copper are classified as inferred resources. The estimates are based on a cutoff grade of 1 gram gold.

At a cutoff of 3 grams, the indicated resource slips to 9.1 million tonnes of 6.6 grams gold, 40 grams silver, and 0.23% copper, with inferred resources of 400,000 tonnes of 4 grams gold, 29 grams silver, and 0.19% copper.

The estimates are based on 37,423 metres worth of drilling in 147 diamond drills holes, including

The latest batch of thirteen drill holes was highlighted by hole no. 226, which yielded multiple mineralized intervals, including a 25.4-metre stretch (beginning 154.3 metes below surface) grading 17.9 grams gold and 49.5 grams silver, and 1.7% copper.

Other selected results include:

• Hole 227 – 4 metres (from 144 metres) averaging 10.1 grams gold, 53.9 grams silver and 0.5% copper;
• Hole 228 – 1.1 metres (from 26 m) running 2.2 grams gold, 2.9 grams silver and 1.7% copper;
• Hole 230 – 10 metres (from 156 m) of 7.6 grams gold, 79.8 grams silver and 0.56% copper, and 4 metres (from 201 m) of 11.6 grams gold, 140.5 grams silver and 0.5% copper;
• Hole 239 – 44 metres (from 139 m) averaging 3.5 grams gold, 40 grams silver and 0.1% copper, and 34.7 metres (from 223.2 m) of 2.3 grams gold, 22.6 grams silver and 0.1% copper.

The remaining holes returned gold grades of 1 to 15 grams, silver grades of 4.5 to 20 grams, and copper grades less than 1% over core lengths of 5 to 80 metres. Two holes were abandoned due to difficulties with the drill rig.

Iamgold CEO Joe Conway says the results also include holes south of the existing resource, indicated the resource figure has the potential to grow.

Drilling earlier this year established that the D1 zone and Loma Larga zone to the south represent a single mineralized structure.

Based on the encouraging results, the company has boosted its 2005 exploration and drilling budget by 36% to $5.3 million.

In late August, SGS Lakefield Research completed metallurgical tests on nine samples with grades ranging from 5 to 42 grams gold, 28 to 131 grams silver, and 0.3 to 5.4% copper. Composite samples were also tested.

SGS’s work concluded that pressure oxidation followed by cyanidation of the residue recovered 99% of the gold and copper from enargite, the main copper-bearing mineral in the Quimsacocha deposit. Low reagent consumption was also indicated.

Initial flotation tests returned gold recovery rates of 94% to 97%, and up to 99% for copper. Subsequent pressure oxidation and cyanidation also yield recovery rates in excess of 95%. Direct cyanidation leach tests continue.