The structural environment of Pb and Zn sorbed from solution onto the surface of chalcopyrite has been studied by XAS both before and after the addition of xanthate. Initially the Pb is bonded as a Pb-O species to the surface sulfur atoms, probably via the hydrophobic S-rich species. After the addition of xanthate, the oxygen bonded to the Pb is displaced and the Pb is coordinated to 4 S atoms. The Zn, in contrast, is initially coordinated only to oxygen atoms on the surface, probably via a Fe(OH)(x)-type species and after xanthate addition it is bonded to ca. 1 O atom and 3 S atoms, the latter provided by the xanthate. These observations help explain the loss of self-flotation of chalcopyrite in the presence of metal ions and the action of the xanthates in restoring its flotability.