Rock Topics

Classification of Metamorphic Rocks (Part 5)

Dark and red-brown crystals of garnet in schist indicate medium-grade metamorphism.  Garnet is an aluminum-rich silicate mineral.

SchisrSchist (Photograph by Parvinder Sethi)

Elongated brown crystals of staurolite in schist indicate medium- to high-grade metamorphism.  Staurolite is commonly known as fairy stone.  Staurolite contains iron, magnesium, aluminum, and silicate. 

StauroliteStaurolite (Photograph by Parvinder Sethi)

Bladed blue crystals of kyanite in schist indicate high-grade metamorphism.  Kyanite is made up of aluminum and silicate.

KyaniteKyanite (Photograph by Parvinder Sethi)