Business: Gypsum & Deflation

A white, nonmetallic mineral is gypsum. It has been used as a building material throughout history. In raw form its principal use is as a retarder in cement, preventing it from setting too rapidly. It is also in wide industrial demand as a flux in smelting, as ''mineral white" or "terra alba'' in the paper, textile and paint trades. Blackboard chalk is raw, powdered gypsum molded with a binding substance. Pure gypsum is alabaster.

Most gypsum, however, is calcined by dehydrating with heat. With 75% of its moisture removed, gypsum becomes plaster of Paris.*...

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