Smokey Quartz

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Smoky Quartz
Chemical composition SiO2 Silicon dioxide
Crystal system Trigonal
Habit Prismatic
Cleavage Poor
Fracture Conchoidal
Hardness 7
Optic nature Uniaxial +
Refractive index 1.544 - 1.553
Birefringence 0.009
Dispersion 0.013
Specific gravity 2.65
Lustre Vitreous
Pleochroism Weak to moderate