[Gk. gypsos, chalk.] Sulphate of lime a common mineral, of which there are large beds in many parts of the United States. When burned and ground it becomes plaster of Paris. Ground gypsum is often used by farmers as a manure. Alabaster is a fine grained white or light-colored gypsum. Satin spar, a beautiful fibrous variety, is used for necklaces and inlaid work.