Soapstone, also known as steatite, is a soft rock composed mostly of the mineral talc. It feels soapy or oily and varies from white to gray and grayish-green.
Soapstone has many industrial uses. It is a good electric insulator and can easily be cut into various shapes. Because soapstone is not affected by high temperatures, or acids, it is used for laboratory table tops, sinks, and some chemical equipment. Powdered soapstone is added to cosmetics, paper, and paint as a filler to improve these products. For example, soapstone gives paper a smooth surface. Tailors use pieces of soapstone called French chalk to mark cloth.
Soapstone is formed in the earth by changes in the structure and composition of an igneous rock such as peridotite (see Igneous rock). These changes occur at low temperature and moderate pressure in the presence of water. Other kinds of rock that usually occur along with soapstone include dolomite and serpentinite. Soapstone, a metamorphic rock, forms in layers that vary greatly in thickness.
The United States ranks among the leading soapstone producers. Deposits occur in several states, including California, New York, North Carolina, and Virginia. Other countries that produce soapstone include Canada, France, and Italy.
See also Talc; Metamorphic rock.
