Gipsas

Gipsas, known in English as gypsum, is a soft sulfate mineral with the chemical formula CaSO4·2H2O. It forms as a hydrated calcium sulfate and is a common rock-forming mineral in sedimentary environments. Gypsum occurs in several forms, including transparent crystals (selenite), fine-grained masses, and more massive varieties such as alabaster. It is typically white or colorless, but can be stained by impurities.

Geological formation and occurrence: Gypsum is deposited from evaporating seawater in sedimentary basins and can be associated with other evaporite minerals such as halite and anhydrite. Large, economically important deposits occur worldwide, including in the United States, Spain, Iran, Canada, and Greece. Gypsum can also form as a secondary mineral through diagenetic processes in sedimentary rocks.

Uses and applications: The most prominent use is in construction, where gypsum is processed into plaster of Paris and gypsum boards (drywall). Calcination removes part of its water to produce calcium sulfate hemihydrate, which sets rapidly with water to revert to gypsum. Other applications include cement manufacture, plaster coatings, and art plaster. Gypsum also serves as a soil amendment to provide calcium and sulfur to plants, improve soil structure, and reduce acidity in some soils.

Processing and properties: Gypsum is mined as rock gypsum and then processed by crushing, grinding, and calcining. It has a Mohs hardness of about 2, is relatively soft, chemically inert, and moderately soluble in water. Dust can irritate the eyes and lungs, so proper handling is recommended.