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16.65: Sphalerite

  • Page ID
    6495
  •  

    Sphalerite
    Chemical composition (Zn,Fe)S
    Crystal system Cubic
    Habit Tetrahedral or dodecahedral
    Cleavage Perfect in 6 directions; easily developed
    Fracture Concoidal to uneven
    Hardness 3.5-4.0
    Optic nature Isotropic
    Refractive index 2.368 - 2.50 (increases with Fe content)
    Specific gravity 3.95-4.10
    Lustre Adamantine to Subadamantine

    Figure \(\PageIndex{1}\): Round Brilliant Sphalerite
    Photo courtesy of
    Rick Martin, Art Cut Gems