A quartzmonzodioritic dike associated with the porphyryCu mineralized stock at Santa Rita, NM, has been studied to constrain physicochemical factors ( P, T, f O 2, and volatile content) responsible for mineralization. The dike contains a lowvariance mineral assemblage of amphibole, plagioclase (An 3050 ), quartz, biotite, sphene, magnetite, and apatite, plus anhydrite and calcite ...