Talc. The mineral talc, also called steatite or soapstone, consists of monoclinic crystals of hydrous magnesium silicate (Mg3Si4O10(OH)2). It is very common, very soft, and usually found in metamorphic rock. In its purest form it is white and greasy to the touch. Finely crushed talc is used to make talcum powder. The mineral is also used in the paper, rubber, paint and textile industries.