Formula: Ca2Fe2+Mg2Fe2+2Be4[(OH)4|(PO4)6] · 6H2O
Reflected/transmitted colour:
Pleochroism: β greenish-brown > α brown > γ brown
Optical isotropy/anisotropy: Biaxial
Optical sign: -
Refractive indices: α = 1.613, β = 1.620, γ = 1.626
Bireflectance/Birefringence δ: 0.013
2V angle: 85° (calculated), 60° (measured)
Dispersion: Not observed
Optical orientation:
Optical axial plane:
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