Talc (powdered magnesium silicate)

Talc is a clay mineral composed of hydrated magnesium silicate with the chemical formula H₂Mg₃(SiO₃)₄ or Mg₃Si₄O₁₀(OH)₂. In loose form, it, along with corn starch, was one of the most widely used substances known as baby powder (in the case of talc, often called simply talcum powder; see litigation.) It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage, and the folia are not elastic, although slightly flexible.