Staurolite is best known for its distinctive, cross-shaped penetration twins, where two rectangular crystals intersect each other to form a perfect cross. However, its most typical twinning habit is in intersecting crystals with a 60° angle that often appear in the shape of an “X”. In fact, this habit is the basis for its name, originating from the Greek term “stauros” which means cross. With its reddish-brown, brown and black color, its vitreous to resinous luster, and its aesthetic crystal cross habit, it is a popular collector’s mineral.
The crystal system for Staurolite is monoclinic, often forming in prismatic penetration twins as mentioned earlier, with a triangular formation on crystal terminations. Other forms include stubby and tabular.
Notable localities for quality Staurolite specimens include Australia, Brazil, Madagascar, Russia, Switzerland and the USA (Georgia, Virginia).