Gypsum (Sulfate)
CaSO2*2H2OHardness: 2.0
Specific Gravity: 2.32
Characteristics: White, gray, or colorless; vitreous or silky luster; transparent to translucent; perfect basal cleavage; often form in elongated massses or rosettes; twinning and crystal intergrowths are common; rarely contains significant impurities.
Found in evaporites; hydrothermal deposits.
Some uses of gypsum include industrial or building plaster; in wallboard; in cement manufacture; and agriculture.
(Primary text: Perkins, D. 2002. Mineralogy. Prentice Hall.)