Mineralogy
| Chemical composition and name | SiO2 – Silicon dioxide |
| Hardness (Mohs scale) | 7 |
| Specific gravity | 2.65–2.667 |
| Refractive index (R.I.) | 1.543–1.552 to 1.545–1.554 |
| Birefringence | 0.009 |
| Optic sign | Positive |
| Optical character | Uniaxial |
Read more about this topic: Onyx