The Softest Mineral: Talc


Talc is the softest known mineral and is listed as 1 on the Mohs hardness scale. It is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. In loose form, it is the widely-used substance known as talcum powder. It occurs as foliated to fibrous masses, its crystals being so rare as to be almost unknown. It can be easily scratched by a fingernail and can be cut with a knife.

Talc is used in many industries such as paper making, plastic, paint and coatings, rubber, food, electric cable, pharmaceuticals, cosmetics, ceramics, etc. A coarse grayish-green high-talc rock is soapstone and has been used for stoves, sinks, electrical switchboards, crayons, soap, etc. It is often used for surfaces of lab counter tops and electrical switchboards because of its resistance to heat, electricity and acids. Talc is used in cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. It is used in baby powder for preventing diaper rashes. It is also often used in basketball to keep a player’s hands dry. Most tailor’s chalk is talc, as well as the chalk often used for welding or metalworking. Talc is also used as food additive or in pharmaceutical products as a glidant. Talc is widely used in the ceramics industry in both bodies and glazes.

Source: Wikipedia