The individual mineral grains in schist, drawn out into flaky scales by heat and pressure, can be seen by the naked eye. Schist is characteristically "foliated", (~leaf-like) meaning the mineral grains split off easily into flakes or slabs. The word "schist" is derived from the Greek word "σχίζειν schíxein" meaning "to split". This refers to the ease with which schists can be split along the plane in which the platy minerals lie.