Targeting Carlin-type gold deposits, junior
The core program will immediately extend a reverse-circulation hole that was drilled in the summer. The hole, which bottomed at 4,200 ft., returned anomalous gold, arsenic and silver values over wide widths, indicating the possible presence of Carlin-type mineralization nearby.
Also, near the hole’s bottom, fracturing and alteration increased in the Lone Mountain dolomite unit, perhaps indicating close proximity to the favorable Robert’s Mountain formation.
Several other targets will be tested during the program, using results from an ongoing geophysical survey.
Between 1987 and 1994, Gold Bar produced 485,000 oz. from 7.5 million tons grading 0.074 oz. per ton. Recoveries are said to have averaged 87%.
American Bonanza has staked an adjacent property that covers 600 acres of favorable structural and stratigraphic targets. The property, which has been mapped, is being incorporated in the geophysical survey.
Meanwhile, American Bonanza is sending a second underground rig and one surface rig to its Copperstone property in Arizona. Current drilling is focused on existing resources in order to bump them up to reserve status.
Earlier this year, the company extended an existing decline some 500 ft. to the southern end of the targeted D zone, which is 600-650 ft. below surface. The extension was made to intersect drill hole C96-19, which returned 5.3 oz. over 10 ft., about 80 ft. north of D zone’s southern margin.
A 1999 scoping study by MRDI Canada estimated the total geological resource for the C and D zones at 2.1 million tons grading 0.34 oz. The D zone alone contains 391,500 oz. gold in an indicated and inferred resource totalling 910,800 tons and averaging 0.43 oz.
Gold grades were capped at 4.7 oz. in the D zone and at 2.5 oz. in the C zone.
Between 1987 and 1993, Cyprus Minerals pulled 514,000 oz. from 5.6 million tons of milling ore and 1.2 million tons of leaching ore using open-pit mining methods. The carbon-in-pulp mill recorded recovery rates of 89%.
Following the mine’s closure, the tailings pond was reclaimed and the CIP mill removed. Some facilities, such as roadways and power lines, remain in service.
In 1993, Santa Fe Pacific had a go at the property but bowed out a year later. Before doing so, it sank 12,500 ft. in 17 widely spaced reverse-circulation holes, of which one cut 15 ft., averaging 0.65 oz., in the footwall of the Copperstone fault, some 479 ft. from surface.
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