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Chemical composition CaB2(SiO4)2

Calcium boro-silicate

Crystal system Orthorhombic
Habit Prismatic
Cleavage Indistinct, basal
Fracture Sub-conchoidal
Hardness 7.0-7.5
Optic nature Biaxial +/-
Refractive index 1.630-1.636
Birefringence 0.006
Dispersion low, 0.017
Specific gravity 3.00
Lustre Vitreous
Pleochroism Weak/not determinable
Fluorescence Light blue (LW)