Details on the Cananea copper deposits appear in several previous papers cited below. The following is taken from Richard H. Sillitoe’s unpublished work dated June 1975, on file in the Council of Mineral Resources (Consejo de Recursos Minerales). The geology was described by Valentine (1936); mineralization and mineral deposit data are by Perry (1935), Velasco (1966), and Cía. Minera de Cananea, S. A. (1973). The breccias were described by Perry (1961). Sillitoe’s comments are summarized below.