Schist, a common metamorphic rock. Schist consists mainly of silicate minerals, chiefly mica, hornblende, talc, or chlorite. Quartz is also usually present. The minerals in schist are arranged in fairly parallel and often wavy layers. Because of its layered structure, schist can be easily split into sheets; the sheets are not smooth, but have an uneven surface. (Its name is derived from a Greek word meaning to split.) The color of schist—varying with its mineral composition—is usually gray, yellow, light or dark green, brown, or black. Most forms of schist are named for the abundant minerals in them. Mica schist, the most common form, is rich in mica and quartz and frequently contains large crystals of garnet or kyanite.
Schist is formed from various igneous or sedimentary rocks under great pressure and heat. It is widely distributed in the earth's crust, but is most common in mountain ranges. Many forms of schist are used as flagstone for fireplaces and patios. Some schists are used as building stone.