1. n. [Geology]

[CaSO472H2O] A highly insoluble sulfate mineral that is the first to precipitate from evaporating seawater. Dehydration of gypsum can produce anhydrite. Fine-grained gypsum is called alabaster.

See related terms: calcium mud,  carbon dioxide,  evaporite,  halite,  hydrate,  scale,  sedimentary