Formula: (Mn,Ca,Mg)Mn3O7.H2O
Reflected/transmitted colour: Gray white (RL)
Pleochroism: Strong to faint, dark brown (X), brownish (Y), yellowish brown (Z)
Optical isotropy/anisotropy: Biaxial, RL very strong anisotropic, bluish or brownish
Optical sign: n.d.
Refractive indices: n = > 2.00
Bireflectance/Birefringence δ: ~ 0.02
2V angle: n.d.
Dispersion:
Optical orientation: Y = b, Z @ c
Optical axial plane:
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