is a medium grade metamorphic rock formed from
shales and slates. The mineral
crystals in a schist have been flattened into visible thin crystals, resulting
in a flaky texture to the rock.
By definition, a schist contains more than 50% of platy and elongated
minerals, usually in a quartz and
feldspar matrix. Note that even these host
minerals may have flattened, distorted crystal shapes.