The dissolution of chalcopyrite is often viewed in terms of passivation. This interpretation has frequently ignored the electronic structure of the mineral, instead treating it simply as a source or sink for electrons. An alternative explanation has been pursued by Crundwell and co-workers, who have presented significant data and analysis to support their views. This alternative viewpoint argues that the events concerning charge-transfer at the interface must be interpreted in terms of the electronic structure of the mineral itself. These authors have argued that this viewpoint is more consistent with the mechanism of the dissolution of other minerals. In this paper, we critically review these opposing viewpoints.