Fumarolic alteration is widespread on the volcanic complex, being conspicuous on the ridge between Olca and Volcan Paruma and on the northern and southeastern flanks. Sulfur is present on the volcano, mainly around Olca, and was mined into the 1980s. Sulfur mines on the Bolivian side include Mina Carlota between Olca and Paruma and Mina Tres Rayas on Olca.