Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO
4 and related
hydrates. In the form of γ-
anhydrite (the
anhydrous form), it is used as a
desiccant. One particular
hydrate is better known as
plaster of Paris, and another occurs naturally as the mineral
gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water.