A common mineral found in sedimentary environments, gypsum is a rock-forming mineral that produces massive beds. Gypsum has several names, including selenite, satin spar and alabaster. Gypsum is one of the more common minerals in sedimentary environments and often includes other minerals.
Gypsum has been used as a building material since the time of the pharaohs. Ancient Egyptians would burn gypsum, then crush it into a fine powder which, when mixed with water, would make an early form of plaster. Egyptians used sheets of gypsum as windows because of its semi-transparent quality. Gypsum was the prime ingredient in roofing plaster used in France (then England), becoming known as plaster of Paris. Present-day usage exceeds 30 billing feet of gypsum panels produced each year in North America alone. A plentiful mineral, vast amounts of gypsum are available. White Sands National Monument in New Mexico is a protected 275-square-mile expanse of sand dunes made up of gypsum crystals.
The fine-grained variety of gypsum is called "alabaster" and has long been used for ornamental work. Alabaster is mined in England and America with rare forms such as black alabaster found in Oklahoma, Italy and China. A soft mineral, it is carved into a variety of shapes and forms. The finest kind of alabaster is Castellina, which is almost exclusively shipped to Florence, Italy for sculpture work. Alabaster has been used for sarcophaguses, perfume bottles and vases. The primary color of alabaster is white.
Gypsum is the main ingredient in plaster of Paris, Portland cement, and most of the sheetrock(wallboard) produced in the United States. As an ingredient in cement, gypsum slows the setting process and creates an necessary binder. Gypsum is preferred over other products for wallboard because of its natural insulation qualities. Nearly all chalk is made of gypsum as it is stronger than talc and is easy to dye.
In agriculture, gypsum is milled into a granular form and applied to compacted or clay soils to chemically break the soils down and promote draining and aeration. Best for dense clays, gypsum loosens the soil by breaking down the minerals, allowing water and air to penetrate. Gypsum also delivers much-needed calcium to plants and can help in offsetting problems with saline soils. Pet-safe, it is commonly prescribed as a treatment for lawns and gardens.
Non-toxic, gypsum is used in food production as a coagulant to make tofu, to condition water, and control tartness in wine. Gypsum has even made its way into the movies, often used in flake form as snow.