gypsum

Common sulfate mineral, hydrated calcium sulfate (CaSO2HO), of great commercial importance. Deposits occur in many countries, but the U.S., Canada, France, Italy, and Britain are among the leading producers. Crude gypsum is used as a fluxing agent, soil conditioner, filler in paper and textiles, and retarder in portland cement. About three-fourths of the total production is calcined for use as plaster of paris and as building materials in plaster, board products, and tiles and blocks.