Andesine
From The Gemology Project
| Andesine | |
|---|---|
| Chemical composition | (Na,Ca)[Al(Si,Al)Si2O8] |
| Crystal system | Triclinic |
| Habit | Prismatic |
| Cleavage | Distinct to perfect |
| Fracture | Conchoidal |
| Hardness | 6.5 |
| Optic nature | Biaxial +/- |
| Refractive index | 1.551 - 1.560 |
| Birefringence | 0.009 |
| Specific gravity | 2.67 |
| Lustre | Sub-vitreous |