Formula: (Ca,K,Ba,Na)3-4Mn24(Si,Al)40(O,OH)112 ·21H2O
Reflected/transmitted colour: Colourless
Pleochroism:
Optical isotropy/anisotropy: Biaxial
Optical sign: -
Refractive indices: β = 1.612
Bireflectance/Birefringence δ:
2V angle: <15°
Dispersion: Slight, r < v
Optical orientation:
Optical axial plane:
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