Gold in porphyry copper deposits: its abundance and fate

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• 作者：Kesler ; Stephen E. ; Chryssoulis ; Stephen L. ; Simon ; Grigore
• 关键词：Gold ; Copper ; Porphyry
• 刊名：Ore Geology Reviews
• 出版年：2002
• 出版时间：October, 2002
• 年：2002
• 卷：21
• 期：1-2
• 页码：103-124
• 全文大小：636 K

文摘

Porphyry copper deposits are among the largest reservoirs of gold in the upper crust and are important potential sources for gold in lower temperature epithermal deposits. Whether gold remains in porphyry copper deposits is important both to their economic attractiveness and to the distribution of gold in the upper crust. Cu/Au atomic ratios of porphyry copper ore deposits form a continuous range from about 5000 to 5,000,000 with a median near 40,000, which separates gold-rich and gold-poor deposits. Gold is found in porphyry copper deposits in solid solution in Cu–Fe and Cu sulfides and as small grains of native gold, usually along boundaries of bornite. SIMS (ion probe) analyses of ore minerals from the gold-rich Batu Hijau, Kingking and Skouries porphyry copper deposits show that bornite contains about 1 ppm Au, whereas chalcopyrite contains about an order of magnitude less. Chalcocite and covellite contain 10–20 ppm Au, but are not abundant enough to account for a significant part of the gold endowment in many porphyry copper deposits. The amount of gold presently in solid solution in Cu–Fe sulfides is not adequate to account for all the gold in porphyry copper deposits, and the remainder is present as micron-scale grains of native gold.