Boleo drilling intersects copper-cobalt zone

Drilling on the Boleo copper-cobalt deposit in Baja California Sur, Mexico, has returned encouraging values from the Saturno open-pit target.

Coeur d’Alene Mines (NYSE) is earning a half interest from International Curator Resources (VSE) by spending up to US$6 million on a feasibility study. The joint venture, in turn, can buy the property outright from a Mexican group.

The drilling was designed to test several prospective areas on the property. Boleo contains a series of flat-lying sediment hosted copper-cobalt beds. Nine holes were drilled on the Saturno open-pit target over an area measuring about 1 by 1 km. The holes intersected a shallow, flat-lying zone averaging 12 metres in thickness and grading 0.50% copper plus 0.07% cobalt on a dry weight basis.

Since the moisture content of the mineralized bed averages 20%, the mining grade would be reduced by an equivalent amount.

Three holes drilled on Boleo Arroyo, another open-pit target, 1-2 km west of Saturno, returned lower-grade values.

Hole 94-36 intersected 4.9 metres grading 0.38% copper and 0.059% cobalt; hole 94-37 returned 13.9 metres grading 0.10% copper and 0.035% cobalt; hole 94-38 intersected 10.2 metres grading 0.27% copper and 0.018% cobalt. One hole on the Santa Rita underground area, about 500 metres south of Saturno, also returned encouraging values.

Hole 94-32 encountered 2.58 metres (76.24-78.82) grading 0.90% copper and 0.10% cobalt, 1.96 metres (97.92-99.92) grading 2.91% copper and 0.16% cobalt plus a further 1.81 metres (186.04-187.85) grading 1.36% copper and 0.021% cobalt.

Work on the Boleo property is primarily focused on the San Guillermo area, which contains an estimated proven and probable underground reserve of 4.8 million tonnes grading 2.9% copper.

Previous work did not test for cobalt, although wide-spaced, infill drilling earlier this year returned cobalt values ranging from 0.003% to 0.14%. The joint venture is reviewing the possibility of heap-leaching the San Guillermo reserve.

Preliminary metallurgical work has returned recoveries of more than 90% for copper and more than 50% for cobalt, using agglomeration with sulphuric acid and ferric cure.

Further metallurgical testing, as well as underground test mining, is continuing.