Determination of minerals in platinum concentrates from the Transvaal by X-ray methods

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Abstract
Concentrates from the platiniferous norites of the Bushveld, Transvaal, are not completely soluble in aqua regia. The insoluble portion consists of steel-grey fragments first analysed chemically by R. A. Cooper and considered by him to be a new platinum mineral represented by the formula Pt(As,S)2. The name cooperite was proposed for the new mineral by F. Wartenweiller, and after further work Cooper decided that the arsenic found in the early analysis was due to the presence of sperrylite, and he changed the formula to PtS2. H. Schneiderhöhn observed simple twinning and, less frequently, polysynthetie lamellae on polished sections of mineral grains from the same deposits, and he suggested that cooperite is probably orthorhombic and isomorphous with marcasite. The latest account of the new mineral has been published by H. R. Adam who gave several analyses of cooperite from the Rustenburg and Potgietersrust districts and concluded that the ‘mineral is PtS2 with a small amount of excess metal (platinum, palladium, and nickel) present in solid solution’.