Quiz: Remember the definition of mal de mer?
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.