Editorial Feature

Zussmanite – Occurrence, Properties and Distribution

Zussmanite was discovered in the year 1964 in the Laytonville Quarry located in the Coastal Range of California, USA. This mineral is named after Jack Zussman, who is a professor at the University of Manchester in England. Zussmanite is isostructural and the Fe-analogue of Coombsite.

Properties of Zussmanite

The key physical properties of Zussmanite are summarised below:

  • Cell Data
    • Space Group - R3 or R3
    • a= 11.6 (2)
    • c=28.69 (2)
    • Z = 3
  • Crystal Data
    • Hexagonal
    • Point Group – 3 or 3
    • Crystals – tabular crystals to about 1 mm.
    • X-ray powder pattern: Laytonville district, California, USA
      9.60 (100), 4.78 (45), 3.19 (25), 2.51 (16), 3.78 (10), 2.74 (10), 2.20 (10).
  • Chemical Composition
    Elements Content 1
    K2O 2.19
    MgO 1.88
    MnO 3.30
    Al2O3 2.37
    FeO 36.81
    SiO2 47.57
    H2O 5.87
  • Optical Properties
    • Translucent
    • Lustre – vitreous
    • Color- pale green in thin section
    • Optical Class – Uniaxial (-)
  • Estimated Properties
    Electron density Bulk density (electron density) = 3.09 g/cm3
    note: Specific gravity of Zussmanite = 3.15 g/cm3
    Photoelectric PEZussmanite = 10.23 barns/electron
    U = PEZussmanite x rho;electron density = 31.62 barns/cm3
    Fermion index Fermion index = 0.01
    Boson index = 0.99

    Radioactivity

    GRapi = 25.83 (Gamma Ray American Petroleum Institute Units)
    Concentration of Zussmanite per GRapi unit = 3.87 %
    Radioactivity of Zussmanite is barely detectable.

How to Identify Zussmanite

The color of zussmanite is pale green in the thin section. This mineral also exhibits a vitreous lustre.

Global Distribution

Zussmanite is found only in the Laytonville quarry located in the Mendocino Co in California, USA.

Occurrence of Zussmanite and Useful Mineral Association

Zussmanite occurs as an exotic block of metamorphosed shales, siliceous ironstones and also impure limestones. This could probably be the representation of the deep ocean sediments that are subjected to blueschist facies metamorphism.

Zussmanite is often associated with minerals such as howieite, spessartine, aegirine, riebeckite, graphite, aragonite etc.

References

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