Formula: (Ca,Na)2[(Mg,Fe,Al,Si)3O7]
Reflected/transmitted colour: colourless
Pleochroism: in thick sections w golden brown, ε colourless to faint yellow
Optical isotropy/anisotropy: uniaxial
Optical sign: +,-
Refractive indices: w = 1.624-1.666, ε = 1.616-1.661
Birefringence δ: 0.001-0.013
2V angle:
Dispersion:
Optical orientation:
Optical axial plane:
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