Facies series with kyanite at middle grade and sillimanite at high grade represents metamorphism at pressures greater than that of the triple point and is referred to as the Barrovian facies series . Chloritoid occurs at low grade and staurolite commonly appears at the same grade as kyanite.
Cordierite appears in the sillimanite zone.
Staurolite and cordierite appear at the same grade as andalusite and chloritoid does not occur. Subhedral porphyroblasts of kyanite and staurolite are concentrated in thin layers of foliated white mica that probably represents clay-rich mud layer in succession of beach sands. Staurolite grains that are colorless may be confused with kyanite, with which it commonly occurs, but kyanite is optically negative. Tiny grains zoned from pale blue-green core to olive brown rim, are tourmaline . Opaque mineral is ilmenite .