SELECTIVE DEPTH ANALYSES OF THE ALTERATION PRODUCTS OF BORNITE, CHALCOPYRITE AND PYRITE PERFORMED BY XPS, AES, RBS

Abstract

The comparative application of three complementary surface analytical techniques allows us to investigate the alteration process and to probe selectively, as a function of depth, the oxidation products of bornite, chalcopyrite and pyrite. Starting from a pristine surface, the samples have been studied at different stages of alteration up to a strongly oxidized state after two years of air exposure. In spite of their different compositions, some similarities exist in their oxidation: iron sulfates seem to be mainly responsible for the increase of alteration whereas copper sulfide layers, due to iron depletion from the subsurface area, act as a barrier to the progress of alteration.