Formula: Ba2CaMgAl2F14
Reflected/transmitted colour: Yellowish brown
Pleochroism: Weak, brownish yellow (X=Y), pale yellow (Z)
Optical isotropy/anisotropy: Biaxial
Optical sign: +
Refractive indices: α = 1.441, β = 1.442, γ = 1.444
Bireflectance/Birefringence δ: 0.003
2V angle: 72° (calculated), 70° (measured)
Dispersion:
Optical orientation: Extinction || perfect cleavage
Optical axial plane: ^ to perfect cleavage
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