Luster is adamantine to greasy. Crystals are translucent to transparent. Terminations are usually poorly developed and appear uneven or pitted. Also, granular and columnar. Cleavage is distinct in two directions lengthwise, prismatic.
Fracture is conchoidal and uneven.
Hardness is 2.5 - 3. Streak is orange-yellow. Best Field Indicators are crystal habit, locality, density, high luster and color.