Typically rocks formed by regional metamorphism have experienced deviatoric stress producing foliations. Rock types such as slate, phyllite, schist, gneiss and granulite are typical of regional metamorphism.
Low-grade metamorphism takes place at temperatures between about 200 to 320oC, and relatively low pressure. Low grade metamorphic rocks are generally characterized by an abundance of hydrous minerals. With increasing grade of metamorphism, the hydrous minerals begin to react with other minerals and/or break down to less hydrous minerals.
