Schist

Metamorphic

Schists are foliated or layered metamorphic rocks. The foliation forms from compressive stresses in the earth perpendicular to the layering. Schists contain abundant quartz, feldspar, and mica. The foliation usually displays aligned minerals like muscovite or biotite mica. Many times in high-grade schists (higher pressure and temperature) porphyroblasts of garnet grow within schist.