Anhydrite (calcium sulfate anhydrous) The anhydrous form of calcium sulfate, anhydrite has the chemical formula CaSO4. Found naturally, as well as being a co-product of a variety of industrial applications including flu gas desulfurization and from the production of hydrofluoric acid. Anhydrite is suitable for a variety of applications including fast setting grouts, self levelling floor compounds and rapid setting cementitious systems.