Formula: NaCa2(Zr,Nb)Si2O7(O,OH,F)2
Reflected/transmitted colour:
Pleochroism:
Optical isotropy/anisotropy: Biaxial
Optical sign: -
Refractive indices: α = 1.7-1.705, β = 1.716-1.72, γ = 1.726-1.728
Bireflectance/Birefringence δ: 0.023-0.026
2V angle: 70-76° (calculated), 70-77° (measured)
Dispersion: Weak, r > v
Optical orientation:
Optical axial plane:
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