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Rubellite 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

A German Film on Crystal Structure of Madagascar Liddicoatite