Supergene or hypogene alteration of a pentlandite-chalcopyrite-pyrite assemblage has resulted in the formation of a number of secondary sulfides. Violarite formed first and occurs pseudomorphically after pentlandite. Alteration later intensified, resulting in the dissolution of violarite, chalcopyrite and pyrite and the concomitant deposition of bravoite, idiomorphic pyrite, anhedral pyrite, marcasite, chalcopyrite, hematite, quartz and carbonate. Bravoite, in contrast to violarite, does not occur pseudomorphically after pentlandite. This relationship is considered to be of general application. The nickel content of each sulfide was determined using an electron microprobe analyzer. Relationships between idiomorphic pyrite and bravoite show that an immiscibility gap may exist between pyrite, with up to 1.5 percent Ni, and bravoite, with 11 to 12 percent Ni.