Mineral - Tourmaline

Name Tourmaline
Class Silicates
Category Mineral
Crystal system Trigonal
Chemical composition Complex: (Na,Ca)(Mg,Fe,Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH,F)₄
Hardness (Mohs scale) 7 to 7.5
Transparency Transparent to opaque
Geographical origin Brazil, Afghanistan, Madagascar, Mozambique, Nigeria, Sri Lanka, United States