Green Beryl
From The Gemology Project
| Green Beryl | |
|---|---|
| Chemical composition | Be3Al2(SiO3)6 Beryllium aluminium silicate |
| Crystal system | Hexagonal |
| Habit | Prismatic |
| Cleavage | Imperfect, basal |
| Hardness | 7.5 |
| Optic nature | Uniaxial - |
| Refractive index | 1.564 - 1.593 |
| Birefringence | 0.005-0.006 |
| Dispersion | Low, 0.014 |
| Specific gravity | 2.68-2.72 |
| Lustre | Vitreous |
| Pleochroism | Weak to distinct |
