Calcium sulfate occurs in nature in form of three different minerals distinguished by the degree of hydration: gypsum (CaSO4·2H2O), hemihydrate (CaSO4·0.5H2O) and anhydrite (CaSO4).

Hemihydrate occurs in two formations of α- and β-type. Among them β-hemihydrate is mainly used to produce gypsum plasterboard since the hydration product of the α-hemihydrate is too brittle to be used as building material /10/.

 — Key Differences. Gypsum is a soft mineral composed of calcium sulfate dihydrate. Anhydrite is also a calcium sulfate mineral, but it lacks water molecules. 15. Gypsum has a variety of uses, from construction (drywall) to agriculture (soil conditioning). Anhydrite is less common and often used in cement. 12.

 — There are three main diagrams that can help us understand this cycle in detail. The first describes the process of water leaving the structure of gypsum to form hemihydrate or anhydrite. The second depicts the temperature-dependent solubility of the calcium sulphates in water.

 — Anhydrous gypsum (calcium sulfate) has a density of approximately 2.96 grams per cubic centimeter (g/cm³). Hydrated gypsum (CaSO4·2H2O) is less dense due to the presence of water molecules within its structure.

The difference between gypsum and anhydrite is that Gypsum is a mineral that is aqueous and contains 2 water molecules, while anhydrite, as it is known, is a mineral that is anhydrous and does not contain water molecules.

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 without water.

 — The difference is that gypsum (CaSO 4 ·2H 2 O) is a hydrous mineral with two attached molecules of water. Anhydrite, as its name implies, is an anhydrous mineral with no attached water molecules (CaSO 4).

 — Anhydrite (CaSO 4) and gypsum (CaSO 4 ·2H 2 O) are the two most abundant minerals of ancient marine evaporite deposits and are also common in non-marine evaporite deposits. Sedimentary gypsum forms by direct precipitation out of evaporating seawater under arid climatic conditions in hydrologically restricted marine …

 — Gypsum, also called hydrated calcium sulphate (CaSO4 · 2H2O) and anhydrite (CaSO4), also called hydrous calcium sulphate are the major minerals in the sedimentary rocks of rock gypsum and rock anhydrite respectively.