Schist: metamorphic rock containing less than 20% feldspar, with a medium to medium-coarse or fine grain size, characterized by a pronounced schistose texture. This means it tends to split and separate easily into thin sheets parallel to regularly arranged planes of the rock’s components, called schistosity planes. Schist forms from the transformation of clay subjected to high temperatures and consistently high unidirectional pressures within the Earth’s crust, causing the mica crystals present to align in a specific direction.
