Formula: K(Li,Mn)2Al4Si4O12(OH)4(F,OH)4
Reflected/transmitted colour:
Pleochroism: Weak; pale yellow (x), colourless (y), colourless (z)
Optical isotropy/anisotropy: Biaxial
Optical sign: -
Refractive indices: α =1.578, β = 1.592, γ = 1.598
Bireflectance/Birefringence δ: 0.020
2V angle: 66° (calculated), 57° (measured)
Dispersion:
Optical orientation:
Optical axial plane:
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