The energy level model of semiconductor electrochemistry is summarized, and is used to inter- pret the literature of the leaching and the anodic electrochemistry of base-metal sulphides. It is stressed that the electronic structure of the solid and the solution must be taken into account in any fundamental interpretation of the anodic behaviour of semiconducting minerals. In semicon- ductors with a band gap greater than i eV, anodic dissolution occurs almost entirely as a result of hole injection into the valence band. In the case of chalcopyrite, which has a band gap of 0.6 eV, both holes and electrons contribute to the dissolution. Fermi-level pinning is used to derive an expression which is consistent with the observed dissolution kinetics of iron-containing sphaler- ites, i.e., first order in iron content in the solid, and halt' order in oxidant concentration in the solution. It is proposed that pyrite resists dissolution because its valence band is a crystal-field band, which is non-bonding, so surface holes in the upper valence band cannot contribute to bond breaking in the solid.