Talc is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2.. It is very soft, with a hardness of 1. Talc is the softest on the Mohs’ scale of mineral hardness, and can be easily scratched by a fingernail. The mineral has a clear or dusty luster, is translucent to opaque, and has a perfect cleavage in one direction. It is not soluble in water, but is slightly soluble in dilute mineral acids. Its color ranges from white to grey, green, or almost silver and it has a distinctly soapy or greasy feel.

The uses of Talc are wide, and besides being a substance in Chinese medicine, it is used as countertops (soapstone), and in electrical switchboards, carvings, paints, rubber, roofing material, ceramics, and talcum powder

Several studies have established preliminary links between talc and pulmonary disorders, lung cancer and ovarian cancer. This is a concern considering its widespread commercial and household use. The U.S. Food and Drug Administration (FDA) considers non-asbestiform talc (talc which does not contain the potentially carcinogenic asbestiform fibers) to be safe.

For use in Chinese medicine, it is recommended that the mineral not be inhaled or injected. In decoction, it should be placed in a separate cloth bag in order to minimize any residual sediment. The good quality mineral is clean and white in color.