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Geosciences LibreTexts

16.14.03: Bi-color

  • Page ID
    4344
  • Bi-color Tourmaline
    Chemical composition Complex borosilicate
    Crystal system Trigonal
    Habit Prismatic
    Cleavage None
    Fracture Conchoidal
    Hardness 7- 7.5
    Optic nature Uniaxial -
    Refractive index 1.62 - 1.64
    Birefringence 0.014 - 0.040
    Dispersion Low, 0.017
    Specific gravity 3.01 - 3.11
    Lustre Vitreous
    Pleochroism Strong

    File:Bi Color2.jpg

    Figure \(\PageIndex{1}\): Bi-color tourmaline
    Photo courtesy of Lembeck Gems