Luster is vitreous to greasy. Specimens are mostly translucent to small crystals being transparent. Crystal System is trigonal. Crystal Habits include pseudocubic and pseudotetragonal rhombohedrons and modified rhombohedrons. Clusters of spherical flakes and tablets are known.
Faces tend to be curved and striated.
Granular or massive formations are also seen. Hardness is 4.5. Streak is white. Associated Minerals include chalcocite , galena , pyrite , sphalerite , covelite , bornite , pyrophyllite and quartz . Best Field Indicators are crystal habit, color, hardness, density and locality.