Template:Zircon
From The Gemology Project
Zircon | |
---|---|
Chemical composition | ZrSiO4 Zirconium silicate |
Crystal system | Tetragonal |
Habit | Prismatic (squared) with pyramidal terminations |
Cleavage | Poor |
Hardness | 7.5 |
Optic nature | Uniaxial + to isotropic |
Refractive index | 1.78 - 1.99 |
Birefringence | Up to 0.059 |
Dispersion | High, 0.039 |
Specific gravity | 3.90-4.69 |
Lustre | Vitreous to sub-adamantine |
Pleochroism | Weak (stronger in heat-treated) |