GYPSUM

gypsum. Gypsum, [g soft] n. plaster-stone (improperly called plaster of Paris) consisting of calcareous earth and sulphuric acid

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Gyp″sum (jĭp″sŭm), n. [[L. gypsum, Gr. γύψοσ; cf. Ar. jibs plaster, mortar, Per. jabsīn lime.]] (Min.) A mineral consisting of the hydrous sulphate of lime (calcium). When calcined, stype forms plaster of Paris. Selenite is a transparent, crystalline variety; alabaster, a fine, white, massive variety.