Can also be reddish or greenish yellow with impurities. Luster is vitreous to more often resinous or earthy in massive forms. Transparency is transparent to translucent. Crystal Habits include mostly massive or powdery forms but well shaped blocky crystals are common. Cleavage is very poor in two directions.
Fracture is conchoidal.
Streak is yellow. Hardness is 2. Associated Minerals are celestite , calcite , aragonite and gypsum . Best Field Indicators are color, odor, heat sensitivity, lack of good cleavage and crystal habit.