Template:Emerald
From The Gemology Project
Emerald | |
---|---|
Chemical composition | Be3Al2(SiO3)6 Beryllium aluminum silicate |
Crystal system | Hexagonal |
Habit | Prismatic |
Cleavage | Imperfect, basal |
Fracture | Conchoidal to uneven |
Hardness | 7.5 (brittle) |
Optic nature | Uniaxial - |
Refractive index | 1.566 - 1.600 |
Birefringence | 0.004 - 0.010 |
Dispersion | Low, 0.014 |
Specific gravity | 2.67 - 2.78 |
Lustre | Vitreous |
Pleochroism | Weak to distinct |