Talc is an extremely soft mineral that may be white, light green, or gray. Manufacturers use ground talc in the making of ceramics, rubber, plastics, and lubricants. Talc serves as a dusting agent to prevent molded products from sticking to the mold and as a coating on finished products. It is also used as a filler in paint, paper, and soap. Cosmetics manufacturers grind pure talc into fine talcum powder. The talc-rich rock steatite, also known as soapstone, serves as an electric insulator, as a liner for furnaces and stoves, and as an acid-proof covering for tables, sinks, and containers.
Talc is so soft that it can be scratched with a fingernail. It defines the softest rating, 1, on the Mohs hardness scale, a ranking of mineral hardness used by geologists. Talc has a distinct greasy or soapy feel. Its chemical formula is Mg3Si4O10(OH)2. It often forms when the minerals olivine, pyroxene, or dolomite react with water under heat and pressure.
