Luster varies from dull to vitreous. The crystals are transparent to translucent. Crystal Habits include the rhombic prism terminated with rhombic pyramid. Less commonly as short prism with pyramidal termination and rarely as thin tabular crystals or compact dull spheres. Cleavage is not apparent.
Fracture is conchoidal.
Distinguishing Features the color change when viewed under incadescent light as opposed to that under fluorescent light.