Formula: BaAl2Si2O8
Reflected/transmitted colour: colourless
Pleochroism: -
Optical isotropy/anisotropy: biaxial
Optical sign: + or -
Refractive indices: α = 1.579-1.589, β = 1.583-1.593, γ = 1.588-1.600
Birefringence δ: 0.009-0.013
2Vγ angle: 83-92°
Dispersion: -
Optical orientation: α Λ z = 3-5°, β = y
Optical axial plane: (010)
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