Bi-color
From The Gemology Project
| Bi-color Tourmaline | |
|---|---|
| Chemical composition | Complex borosilicate |
| Crystal system | Trigonal |
| Habit | Prismatic |
| Cleavage | None |
| Fracture | Conchoidal |
| Hardness | 7- 7.5 |
| Optic nature | Uniaxial - |
| Refractive index | 1.62 - 1.64 |
| Birefringence | 0.014 - 0.040 |
| Dispersion | Low, 0.017 |
| Specific gravity | 3.01 - 3.11 |
| Lustre | Vitreous |
| Pleochroism | Strong |
Properties in table to be verified please!
