schist

noun

1. any of a class of crystalline metamorphic rocks whose constituent mineral grains have a more or less parallel or foliated arrangement.

noun

1. any metamorphic rock that can be split into thin layers because its micaceous minerals have become aligned in thin parallel bands

n.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 and Scott says Greek skhistos lithos was “probably talc.”

1. A highly foliated, medium-grained metamorphic rock that splits easily into flakes or slabs along well-defined planes of mica. The mineral composition of schist is varied and is often reflected in the name given to the rock. For example, a schist that contains garnet is called a garnet schist. A schist containing chlorite is called a chlorite schist.