Talc is a metamorphic rock, which means it was originally a different kind of rock that changed under heat and pressure. Talc is composed of hydrated magnesium silicate, and its chemical formula is Mg3Si4O10(OH)2.
In the cosmetics industry, talc is used in the making of talcum powder, blushes and eye shadow. Talc is also used in the production of paper, interior and exterior paints and in the manufacture of plastics. Soapstone, a variant comprised mostly of talc, is soft enough to allow for carving into ornamental shapes. With a rating of one on the Mohs hardness scale, it is the softest mineral known and can be scratched with a fingernail.