Abstract

The ores of this deposit show an unusual amount of oxidation and secondary enrichment believed to have taken place during pre-Cambrian time. The ore minerals approximately in order of abundance are: chalcocite, cuprite, malachite, azurite, native copper, chrysocolla, pyrite, chalcopyrite, black oxide, covellite, and bornite. Primary sulphides are pyrite, chalcopyrite, and presumably bornite. The secondary sulphide ore is almost entirely chalcocite, but a little bornite and covellite are found. Malachite commonly replaced chalcocite directly but also replaced cuprite and occurs as nodular and boulder-like masses as well as in streaks in kaolinite. Azurite formed with malachite apparently in much the same sequence except that it was not found replacing sulphides. Cuprite directly replaces sulphides and is commonly replaced by malachite. Chrysocolla occurs mainly with malachite, and native copper also formed at places during oxidation.No peculiarities or changes were noted that might be attributed to the pre-Cambrian age of the oxidation. The minerals, their sequence and textural relations seem entirely normal.

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