Crystals are translucent to opaque in more massive specimens. Crystal System is orthorhombic. Crystal Habits include prismatic to fibrous and compact aggregates forming tufts and radiating sprays. Also massive and granular. Individual crystals are complexly faceted.
Cleavage is perfect.
Fracture is uneven. Hardness is 2.5 - 3. Streak is white. Associated Minerals include quartz , stibnite , native antimony , senarmontite , kermesite , stibiconite and other antimony minerals. Best Field Indicators are crystal habit, high luster, associations and specific gravity.