GOLD PYRITE ASSOCIATION - RESULT OF OXYSULFIDE AND POLYSULFIDE TRANSPORT OF GOLD

Native gold at Comet mine, New South Wales, Australia, is present in t wo parageneses: with quartz and bismuth tellurides; and with pyrite, i ron thiosulphates, calcium sulphates and hematite. Gold of the second paragenesis contains admixtures of S and Fe. At the Main Reef Complex, Barberton, South Africa, gold-bearing pyrite contains relicts of thio sulphates and zones rich in cloudy inclusions of quartz, mica, chlorit e and thiosulphates. Gold occurs as inclusions in the pyrite and is in tergrown with chalcopyrite, tetrahedrite, arsenopyrite, pyrrhotite, an hydrite and hematite. At Dave's Hill mine, Pilgrim's Rest, Transvaal, South Africa, thiosulphates form nests and hairlike veinlets in gold-b earing pyrite and gold occurs as inclusions in pyrite and as intergrow ths with other sulphides. Thiosulphates, sulphates and sulphites have been determined by electron-microprobe analysis using SKalpha and SKbe ta peak shifts and valency-related satellite peaks. Gold in the three locations considered is of a high fineness and the association with th iosulphates suggests that gold thiosulphate complexes were involved in the transport, deposition or redeposition of the element. Pyrite that formed coevally with thiosulphates characteristically contains cloudy inclusions of such phases and is intimately associated with gold, whi ch suggests that pyrite textures may be used to differentiate between gold-bearing and gold-free pyrite.