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Indicolite Tourmaline
Chemical composition Complex borosilicate
Crystal system Trigonal
Habit Prismatic
Cleavage None
Fracture Conchoidal
Hardness 7.5
Optic nature Uniaxial -
Refractive index 1.62 - 1.64
Birefringence 0.014 - 0.022
Dispersion Low, 0.018
Specific gravity 3.06
Lustre Vitreous
Pleochroism Weak to strong
Indicolite Tourmaline
Photo courtesy of Lembeck Gems