Luster is submetallic. Transparency crystals are opaque. The crystals are elongated along the b axis and are generally flattened in the a axis direction. Also as columnar aggregates and lamellar masses. Cleavage is perfect in one direction parallel to the a and c axes.
Fracture is uneven.
Hardness is 4 - 4.5. Streak is black. Associated Minerals are quartz , hematite , tourmalines , cassiterite , micas and pyrite . Best Field Indicators are crystal habit, color, density, luster and cleavage.