Alteration and regeneration of sulfides by reaction with oxidizing hydrothermal solutions

Reactions between sulfides of heavy metals and solutions of hexavalent uranium sulfate at pH about 2, in the range of 200-360°C, led to replacement of pyrrhotite by marcasite-pyrite aggregate, development of bornite and pyrite after chalcopyrite, growth of regenerated chalcopyrite on the periphery of uranium oxides, replacement of chalcopyrite by bornite (with the accompanying complications, fig. 3), redepositions of chalcocite and native copper, and, in experiments with pyrite-galena and galena-marmatite pairs, redepositions of the minerals with the corresponding growth of pyrite. —V.P. Sokoloff.