Stephanite with pen for scale. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew Silver.)

Formula: Ag5SbS4 Orthorhombic


Stephanite is a rare black mineral formed in silver-rich hydrothermal deposits.

FOREST COUNTY: Stephanite occurs at the Crandon massive sulfide deposit, near Little Sand Lake. The mineral occurs with polybasite-pearceite and tetrahedrite-tennantite as very tiny grains intergrown with galena (Lambe and Rowe, 1989).