Cominco Res. pulls good hole at Buckhorn mine in Nevada

Following closely on the decision to develop its Maria copper deposit in Mexico, Cominco Resources International has released another good hole from its Buckhorn mine in Nevada. At this point the discovery appears to have some small mine potential, probably on a par with its Mexican property which is predominantly copper.

Many analysts were disappointed with the last hole Cominco announced from Buckhorn which averaged 0.08 oz gold over 40 ft; but recent results show that it takes more than one hole to make or break a potential mine. Among the latest results, hole No 91 returned 30 ft grading 0.7 oz gold from 465-495 ft. It was drilled 50 ft south of hole No 80 which averaged 1.1 oz over 55 ft, the best to date. Hole No 92, which was drilled 50 ft west of No 80, failed to intersect any high grade mineralization.

The recent high grade intersection was a bit deeper and suggests the zone might dip to the southeast. But all holes are vertical and it will probably take an angled hole to accurately determine the vertical extent of the zone, says Cominco Resources.

Follow-up drilling is planned and the company says more results will be released “when the next sequence of holes is completed and a better understanding of the distribution of mineralization is available.” Vancouver-based Equinox Resources has a 23.6% interest in the Buckhorn mine while Bar Resources has a 20% net profits interest. In another important development, Cominco has concluded an agreement with its Mexican partner to bring the high grade Maria copper deposit into production within two years. Empresas Frisco, which Cominco describes as one of Mexico’s “foremost mining companies,” can earn a 51% interest in the project by providing $4.8 million to develop the mine.

The exceptionally high grade deposit is located near Cananea in Sonora State. Reserves are estimated to be 850,000 tons grading approximately 10% cop per, 0.26% molybdenum, and 1.6 oz silver per ton. The mineralized zone lies horizontally about 300 ft below surface and is associated with a larger 8-million-ton porphyry deposit averaging 1% copper which is not economic at present. A reserve of 950,000 tons grading 1.8% copper, 0.44% molybdenum and 0.3 oz silver exists below the high grade deposit.

According to Geoffrey Harden, a vice-president at Cominco Resources, the property could be in production by mid-1989. The decision to sink a shaft or drive a ramp into the ore zone will determine the exact time, however. Shaft access would speed up the process, he notes.

The production rate is expected to be about 300 tons per day and the ore will be trucked to Frisco’s Cumobabi mine near Cumpas where copper and molybdenum concentrates would be produced. That mining operation is approximately 190 (paved) road miles away but Mr Harden says Mexican trucking costs are relatively cheap and should average about $7(US) per ton.

There could be some pre- concentration on site which would reduce the volume of material shipped. The metallurgy of the coarse high grade deposit is excellent and the silver will come out with the copper. Mr Harden is optimistic they will be able to find other shallow high grade deposits on the property.