Formula: (Mn,Ca,Zn)5(AsO4)2[AsO3(OH)]2.4H2O
Reflected/transmitted colour: Colourless
Pleochroism: Moderate, very pale orange-pink (X), exceedingly pale orange-pink (Y), pale orange-pink (Z)
Optical isotropy/anisotropy: Biaxial
Optical sign: -
Refractive indices: α = 1.713, β = 1.723, γ = 1.729
Bireflectance/Birefringence δ: 0.016
2V angle: 75-75.6° (calculated), 70.5-76° (measured)
Dispersion:
Optical orientation: X = b, Y Ù c = 30-40°
Optical axial plane:
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