Formula: Ca12Mn4B2Be18Si12O46(OH,Cl)30
Reflected/transmitted colour:
Pleochroism:
Optical isotropy/anisotropy: Biaxial
Optical sign: -
Refractive indices: α = 1.619, β = 1.631, γ = 1.641
Bireflectance/Birefringence δ: 0.022
2V angle: 84° (calculated), 85° (measured)
Dispersion: Strong, r < v
Optical orientation:
Optical axial plane:
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