metamorphic rock, formed from heat and pressure deep within the Earth's crust. The predominant mineral is crystal which is aligned in parallel layers

A metamorphic rock rich in feldspar, quartz, and mica formed under moderate pressure and low to moderate temperature.

Crystalline rocks whose constituent minerals are arranged in layers which are easily separated.

A strongly foliated crystalline rock which readily splits into sheets or slabs as a result of the planar alignment of the constituent crystals.

low- or medium-grade metamorphic rocks composed of mica-type minerals (mainly muscovite and biotite but also sericite, illite, and chlorite). The term schist includes phyllites, mica schists, and several other metamorphic rock types