Gypsum isposed of hydrated calcium sulfate, and its chemical formula is CaSO 4.2H 2 O. It is a natural salt mineral, that is to say, an evaporite mineral, and is mostly found along with halite, sulphur, 4FeycgduHhrp Drywall is a panel made of calcium sulfate dihydrate, with or without additives, typically extruded between thick sheets of facer ...