Template:Andalusite

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Andalusite
Chemical composition Al2SiO5
Crystal system Orthorhombic
Habit Prismatic
Cleavage Distinct
Fracture Sub-conchoidal
Hardness 7.5
Optic nature Biaxial -
Refractive index 1.63-1.64
Birefringence 0.010
Dispersion Low, 0.016
Specific gravity 3.18
Lustre Vitreous
Pleochroism Very strong