Mineral - Dumortierite

Name Dumortierite
Class Borates
Category Mineral
Crystal system Orthorhombic
Chemical composition Aluminum borosilicate (Al₇BO₃(SiO₄)₃O₃)
Hardness (Mohs scale) 7 to 8.5
Transparency Translucent to opaque
Geographical origin Brazil, Madagascar, France, Russia, United States, Sri Lanka