Talc or talcum is a clay mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. In loose form, it was one of the most widely used substances known as baby powder, along with corn starch. It occurs as foliated to fibrous masses, and in an exceptionally rare crystalform. It has a perfect basal cleavage, and the folia are not elastic, although slightly flexible.
Talc is used in many industries, including paper making, plastic, paint and coatings, rubber, food, electric cable, pharmaceuticals, cosmetics, and ceramics. A coarse grayish-green high-talc rock is soapstone or steatite, used for stoves, sinks, electrical switchboards, crayons, soap, etc. It is often used for surfaces of laboratory table tops and electrical switchboards because of its resistance to heat, electricity and acids. Talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. It is used to coat the insides of inner tubes and rubber gloves during manufacture to keep the surfaces from sticking. Talc, with heavy refinement, has been used in baby powder, an astringent powder used to prevent diaper rash.