Formula: H(Ca,Mn,Fe)Fe3(AsO4,PO4)4.7H2O
Reflected/transmitted colour:
Pleochroism: Pale yellow green (x), pale yellow green (y), medium yellow green (z)
Optical isotropy/anisotropy: Biaxial
Optical sign: +
Refractive indices: β = 1.738, γ = 1.779
Bireflectance/Birefringence δ:
2V angle:
Dispersion:
Optical orientation:
Optical axial plane:
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