Color zoning is apparent on some crystals. Color varies from pale brown, yellow, pink, orange and almost colorless. Luster is vitreous to dull. Diaphaneity is transparent in small crystals, opaque on larger crystals. Crystal Habits include sharp tetragonal bipyramids up to 2cm across and crystals of varied habits.
Fracture is uneven to subconchoidal.
Streak is white. Known since antiquity.