Mineral - Sardonyx

Name Sardonyx
Class Semi-precious
Category Microcrystalline quartz (variety of chalcedony)
Crystal system Trigonal
Chemical composition SiO₂ (Silicon dioxide)
Hardness (Mohs scale) 6.5 to 7
Transparency Translucent to opaque
Geographical origin Brazil, India, Uruguay, United States, Germany, Czech Republic