(Science: chemical) A soft mineral of a soapy feel and a greenish, whitish, or grayish colour, usually occurring in foliated masses. It is hydrous silicate of magnesia. Steatite, or soapstone, is a compact granular variety. Indurated talc, an impure, slaty talc, with a nearly compact texture, and greater hardness than common talc.
Synonym: talc slate.
Origin: F. Talc; cf. Sp. & It. Talco, LL. Talcus; all fr. Ar. Talq.