schist (n.) Look up schist at Dictionary.com
1795 (earlier schistus, c.1600), from French schiste, 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 and Scott says Greek skhistos lithos was "probably talc."