schist (n.) Look up schist at Dictionary.com
type of layered metamorphic rock, 1795 (earlier schistus, c.1600), from French schiste (16c.), from Latin schistos lapis "stone that splits easily" (Pliny), from Greek skhistos "divided, separated," from skhizein "to split" (see shed (v.)). The rock splits easily in layers. Liddell & Scott say Greek skhistos lithos was "probably talc."