Color is usually white to whitish-gray. Luster is vitreous to silky to dull. Diaphaneity is translucent to opaque. Crystal Habits include compact spheres and botyroidal aggregates to 2mm.
Fracture is uneven to subconchoidal.
Hardness is 4.5 - 5. Streak is white. Associated Minerals include galena, natrolite and wulfenite.