What is Gypsum? Gypsum is an evaporite mineral most commonly found in layered sedimentary deposits in association with halite, anhydrite, sulfur, calcite, and dolomite.Gypsum (CaSO 4. 2H 2 O) is very similar to Anhydrite (CaSO 4).The chemical difference is that gypsum contains two waters and anhydrite is …
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