- a very common mineral, hydrated calcium sulfate, CaSO4⋅2H2O, occurring in crystals and in masses, soft enough to be scratched by the fingernail: used to make plaster of Paris, as an ornamental material, as a fertilizer, etc.
- a colourless or white mineral sometimes tinted by impurities, found in beds as an evaporite. It is used in the manufacture of plaster of Paris, cement, paint, school chalk, glass, and fertilizer. Composition: hydrated calcium sulphate. Formula: CaSO 4 .2H 2 O. Crystal structure: monoclinic
substance (hydrated calcium sulphate) used in making plaster, late 14c., from Latin gypsum, from Greek gypsos “chalk,” according to Klein, perhaps of Semitic origin (cf. Arabic jibs, Hebrew gephes “plaster”).
- A colorless, white, or pinkish mineral. Gypsum occurs as individual blade-shaped crystals or as massive beds in sedimentary rocks, especially those formed through the evaporation of saline-rich water. It is used in manufacturing plasterboard, cement, and fertilizers. Chemical formula: CaSO4·2H2O.