Cobaltite. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 337. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew Silver.)

Formula: CoAsS Orthorhombic


Cobaltite is a rare mineral found as silvery metallic grains in hydrothermal deposits. When present in sufficient quantities, it is used as an ore of cobalt.

LAFAYETTE COUNTY: Cobaltite (or possibly safflorite -CoAs2) was observed as microscopic intergrowths with marcasite as the Martin Mine, south of Benton (SW SE Sec.16 T.1N R.1E) (Heyl et al., 1959). The authors speculate that the mineral could be more widespread than recognized in the Upper Mississippi Valley zinc-lead district. Their evidence is the persistent presence of As in the sulfuric acid produced from the district. The material from the Martin Mine weathers to a complex mixture likely containing erythrite. -Reported as a component of the zinc ore body in the Thompson-Temperly Mine at the SW edge of New Diggings (Hosterman, Heyl and Jolly, 1964).