Gypsum (Greek: γύψος, gypsos, meaning "chalk" or "plaster) is a sulfate mineral, very soft, composed of calcium sulfate dihydrate. Its chemical formula is CaSO4·2H2O. It is one of the most widely used minerals in the world, literally surrounds us every day. Most gypsum in the United States is used to make wallboard for homes, offices, and commercial buildings; a typical new American home contains more than 7 metric tons of gypsum alone. Moreover, gypsum is used worldwide in concrete for highways, bridges, buildings, and many other structures that are part of our everyday life. Gypsum also is used extensively as a soil conditioner on large tracts of land in suburban areas, as well as in agricultural regions.
The term alabaster is applied to both the gypsum, a hydrous sulfate of calcium, as the calcite, a carbonate of calcium, also known as onyx-marble. In general, but not always, ancient "alabaster" in Egypt and the Near & Middle East is calcite (often called oriental alabaster), "alabaster" in medieval Europe is gypsum, and modern "alabaster" is probably calcite, but might be either. The Greek words ἀλάβαστρος, alabastros or ἀλάβαστος, alabastos occurs in the Bible in three passages (Matthew 26:7 , Mark 14:3 and Luke 7:37 ) and was usually crystalline stalagmitic rock or carbonate of lime while in modern mineralogy alabaster is crystalline gypsum or sulphate of lime.
- Gypsum: Statistics and Information U.S. Geological Survey. Web. Last Modified: March 7, 2013.