Selective oxidation of minerals was investigated as a means to separate by flotation the copper sulfide minerals of chalcocite, covellite and chalcopyrite from the arsenic copper sulfide minerals of enargite and tennantite in mixed mineral systems. It was found that a separation of these minerals could be feasible after selective oxidation of their surfaces in slightly acidic pH conditions, or after oxidation and selective dissolution of the surface oxidation products with a complexant in basic pH conditions. (C) 2001 Elsevier Science B.V. All rights reserved.