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Chemical composition Be3Al2(SiO3)6 Beryllium aluminium silicate
Crystal system Hexagonal
Habit Prismatic
Cleavage Poor, basal
Fracture Conchoidal to uneven
Hardness 7.5
Optic nature Unixaial -
Refractive index 1.58 - 1.60
Birefringence 0.008 - 0.009
Dispersion Low, 0.014
Specific gravity 2.80 - 2.90
Lustre Vitreous
Pleochroism Weak to moderate (shades of body color)