Reserves on rise at Sleeping Giant

Deep exploration and definition drilling have led to a substantial increase in minable reserves at the Sleeping Giant gold mine, 80 km from Amos, Que.

That’s good news for Cambior (TSE), which spent $12 million to acquire a half interest in the project, based on a mid-1990 agreement with partner Aurizon Mines (TSE).

Cambior suspended production in 1991 as a result of declining reserves (and failure to replenish reserves exploited by Aurizon and its predecessors in the previous 2.5 years of production).

Sleeping Giant was reawakened in May, 1993, after Cambior discovered additional reserves near production workings. Farther from the mine site, an airborne geophysical survey identified an intrusive feature associated with geochemical anomalies of the type known to host other gold deposits in the Abitibi belt.

At the end of 1993, proven and probable reserves were reported as being 375,000 tonnes grading 8.2 grams gold per tonne (93,700 oz. gold in situ). Recent work has expanded the proven and probable minable reserves to 675,000 tonnes grading 9.4 grams (203,400 oz. in situ). This represents a 117% increase in contained ounces since the end of 1993.

The partners are particularly encouraged by deep drilling in the Zone 20 and 30 extension, which identified 275,000 tonnes grading 11.1 grams (98,200 oz. in situ); this tonnage is included in the recent reserve calculation. The flat holes, each measuring 800 metres long, were aimed at outlining en echelon veins.

Cambior has already started extending the shaft by about 300 metres, which should be completed in the first quarter of 1995. The partners plan to invest $7.3 million before the new year in an effort to extend the shaft further and develop five new levels. The development will allow for the establishment of new drilling bases to test the potential of Zones 20 and 30 at depth. “We think the potential to increase reserves is a definite,” Aurizon Vice-president John Harvey tells The Northern Miner. “We were still in the higher-grade material when we stopped, because we had (outlined) enough to make it economic to sink the shaft.”

From mid-July, 1993, when production resumed, to year-end, Sleeping Giant produced 22,896 oz. from the milling of 90,600 tonnes grading 8.5 grams. The unit production cost for the year was US$198 per oz.

In the first eight months of this year, the mine turned out 26,841 oz. from the milling of 78,950 tonnes grading 11.1 grams. The unit cost has been US$194 per oz., and shrinkage stoping continues to be the primary mining method.