Drilling of the western extension of the Big Gossan copper-gold deposit in Indonesia has returned high-grade values for Freeport-McMoRan Copper & Gold (NYSE).
Situated 1 km from the company’s mill on the island of New Guinea, Big Gossan contains 8.5 million tonnes grading 2.4% copper and 0.77 gram gold per tonne.
The total geologic resource is estimated at 32 million tonnes averaging 2.9% copper and 0.91 gram gold.
Underground fan delineation drilling, stepped out at 50-metre intervals, continues to define the deposit to the west. At drill site No. 27, two drill holes averaged 5.6% copper and 2.24 grams gold over 233 metres. At site No. 28, two holes averaged 10.4% copper and 4 grams gold. The resource between the two drill fans is estimated to contain 500 million lb. copper and 300,000 oz. gold.
Big Gossan, which is in the original Block A, remains open to the west and at depth.
Exploration, including diamond drilling, continues on Freeport’s two other land packages, the 2.6-million-hectare Block B and the 1-million-hectare eastern block.
Expansion of the company’s mill to 115,000 from 71,500 tonnes per day is to be achieved in the second half of 1995. As a result, annual production of copper and gold is expected to rise to 1.1 billion lb. and 1.5 million oz., respectively. The Grasberg open-pit deposit is currently supplying most of the mill feed.
Proven and probable reserves at Grasberg are estimated at 977 million tonnes averaging 1.25% copper and 1.55 grams gold.
Freeport holds an 86% interest in Blocks A and B, and a 84.9% interest in the eastern block. The remaining interests are held by the Indonesian government and private Indonesians.
Freeport-McMoRan Gold & Copper is 68%-owned by Freeport-McMoRan (NYSE). An exploration budget of US$40 million is planned for 1995.
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