Definitions for "Gypsum"
A mineral consisting of the hydrous sulphate of lime (calcium). When calcined, it forms plaster of Paris. Selenite is a transparent, crystalline variety; alabaster, a fine, white, massive variety.
Hydrated calcium sulphate; the mineral often appears as outward-curving flowers which have the shape of a petal. The rock is softer than limestone.
A white mineral usually used to make Plaster of Paris.
(13) -- a soft stone used in Minoan architecture (Biers, 336) Sample Image (Lesson 13)
Keywords:  opal, impurity, needle, crystal, stone
Common impurity in opal, a needle-like crystal of this may go right through the stone.
Soil amendment, gypsum board, absorbent media
Keywords:  dry, wall, see
see Dry wall