metamorphism in rocks such as mica schists, slates, and gneisses, where it is generally associated with other minerals.
Staurolite is a brittle, hard mineral that has a dull lustre. Its crystals are usually dark brown and are often twinned in cruciform patterns (known as fairy crosses) that can be made into ornaments. Staurolite occurs especially in Canada, Brazil, France, Switzerland, and the U.S. (North Carolina, Virginia, and Georgia).