Luster is vitreous. Crystals are transparent to translucent. Crystal System is monoclinic. Crystal Habits include tabular or acicular crystals, radiating fibrous and massive crusts. Cleavage is perfect.
Fracture is uneven.
Streak is white. Associated Minerals are kottigite , pyrite and symplesite Notable Occurrences include Alsace, France and Japan. Best Field Indicators are color, crystal habit, cleavage, softness and associations.