Gypsum is an evaporite mineral most commonly found in layered sedimentary deposits in association with Halite, Anhydrite, Sulfur, Calcite and Dolomite. Gypsum (CaSO4.2H2O) is very similar to Anhydrite (CaSO4). The chemical difference is that Gypsum contains two waters and Anhydrite is without water. Gypsum is the most common sulfate mineral. Gypsum uses include: manufacture of wallboard, cement, plaster of Paris, soil conditioning, a hardening retarder in Portland cement. Varieties of Gypsum known as “Satin Spar” and “Labaster” are used for a variety of ornamental purposes; however, their low limits their durability.
Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks. Gypsum is deposited from lake and sea water, as well as in hot springs, from volcanic vapors and sulfate solutions in veins. Hydrothermal Anhydrite in veins is commonly hydrated to Gypsum by groundwater in near-surface exposures. It is often associated with the minerals Halite and Sulfur. Gypsum is the commonest sulfate mineral. Pure Gypsum is white, but other substances found as impurities may give a wide range of colors to local deposits.