Talc
Talc, a common mineral, composed of magnesium, silica (silicon dioxide), and water. Talc is similar to mica in that it is composed of layers that can be easily separated into thin sheets. It has a greasy or soapy feel, and is easily cut with a knife. It is silvery-white, gray, or light green in color and has a pearly luster. Talc is a poor conductor of electricity and heat, is acid-resistant, absorbs oil, and can withstand relatively high temperatures.
The talc-group minerals include talc, pyrophyllite, and soapstone. Pyrophyllite is an aluminum silicate similar in properties, structure, and uses to talc. Soapstone consists of talc mixed with other minerals. Leading producers of these minerals are Japan, the United States, China, and North Korea.
Uses of TalcA major use of talc is in ceramics to improve their firing properties. Another major use is as a filler in paints, plastics, paper, and insecticides. Talc is also used in cosmetic creams and soaps, as a pigment in paints, as a lubricant, and as a mild abrasive. A finely powdered talc known as talcum powder is used as a cosmetic and as a protective application for minor skin irritations. Marking crayons and gas-burner tips are made from solid talc.
Steatite, an impure, compact form of talc, is widely used to make electrical insulators. A whitish variety of steatite known as French chalk is used by tailors to mark cloth before cutting. French chalk is also used to remove grease stains in dry cleaning.
Chemical formula for talc: Mg3Si4O10(OH)2.