Formula:
Reflected/transmitted colour: colourless, pale brwon, pale purplish brown, pale greenish brown or pale green
Pleochroism: more strongly coloured varieties show weak to moderate pleochroism, titanium-augite moderate to strong, α pale greenish, pale brownish, green, greenish yellow, β pale brown, pale yellow-green, violet, γ pale green, grayish green, violet
Optical isotropy/anisotropy: biaxial
Optical sign: +
Refractive indices: α = 1. 671-1.735, β = 1.672-1.741, γ 1.703-1.774
Birefringence δ: 0.018-0.033
2Vγ angle: 25-61°
Dispersion: r > v, weak to moderate, strong in Ti-augite
Optical orientation: α Λ x = 20-35°, β = y, γ Λ z = 35-48°
Optical axial plane: (0-10)
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