Regional metamorphism primarily occurs over large areas under high pressure and temperature conditions, often associated with tectonic processes such as mountain building. The rock type that is uniquely formed through this process is called schist.
Schist is characterized by its pronounced foliation and crystalline texture, which result from the realignment of minerals under directed pressure. This realignment gives schist its distinctive layered appearance. While other metamorphic rocks like gneiss and slate can also come from metamorphic processes, schist is specifically known for its formation under regional metamorphic conditions, setting it apart from those formed by contact metamorphism.