Formula: Mg(OH,F)2.4Mg2(SiO4)
Reflected/transmitted colour: colourless to yellow
Pleochroism: α golden yellow, deep reddish yellow, β pale yellow, orange-yellow, pale yellowish red, γ pale yellow, orange-yellow, colourless
Optical isotropy/anisotropy: biaxial
Optical sign: +
Refractive indices: α = 1.628-1.638, β = 1.641-1.654, γ = 1.662-1.674
Birefringence δ: 0.028-0.041
2V angle: 73-76°
Dispersion: r > v, strong
Optical orientation: α Λ z 9-15°, β = x, γ = y
Optical axial plane: ~ (100)
| Back to Alphabetical list | Colour photos | Physical, chemical and crystallographic description | SEM images | TEM images | vibrational spectra description | IR spectra | Raman spectra | N-IR spectra | F-IR spectra | IES spectra |