Color is usually beige to dark brown on the acicular crystals and varies from very deep red to dark brown on the tabular crystals. Luster is vitreous on tabular crystals and dull to greasy on acicular crystals. Diaphaneity is transparent to translucent on tabular crystals and opaque on acicular crystals. Crystal Habits include sharp, thin tabular crystals to 4mm and aggregates of radiating individual crystals.
Fracture is conchoidal to uneven.
Hardness is 5.5 - 6. Streak is gray. Associated Minerals include calcite, chlorite group, dolomite and quartz.