Formula: (Na,Ca,Mn)(Mn,Fe)(Fe,Fe,Mg)Al(PO4)3
Reflected/transmitted colour:
Pleochroism: Colourless (x), bluish green (y,z)
Optical isotropy/anisotropy: Biaxial
Optical sign: +
Refractive indices: α = 1.685, β = 1.688, γ = 1.692
Bireflectance/Birefringence δ: 0.007
2V angle: 82° (calculated), 90° (measured)
Dispersion:
Optical orientation:
Optical axial plane:
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