Formula: (Ca,Ce)4(Na,Ca)3Ti(Si2O7)2(O,F)4
Reflected/transmitted colour:
Pleochroism:
Optical isotropy/anisotropy: Biaxial
Optical sign: +
Refractive indices: a=1.665, b=1.668, g=1.681
Bireflectance/Birefringence δ: 0.016
2V angle: 52.2° (calculated), 43° (measured)
Dispersion: Strong, r < v
Optical orientation:
Optical axial plane:
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