Luster is vitreous. Transparency crystals are transparent to translucent. Crystal Habits include the tabular, rectangular box formed by three pinacoids, often elongated in one direction forming a prismatic crystal. Most commonly massive and granular. Cleavage is in three directions forming rectangles, but perfect in one, very good in another and only marginally good in the third direction.
Fracture is conchoidal.
Streak is white. Associated Minerals are calcite , halite , and ocassionally sulfides such as galena and pyrite . Best Field Indicators are crystal habit, rectangular and non-uniform cleavage and low density.