Ellisite - Occurrence, Properties, and Distribution

Ellisite is a trigonal-ditrigonal pyramidal dark gray mineral containing thallium, sulfur and arsenic. It was first discovered from Carlin gold deposit, Nevada, USA in 1979. It was named for Albert J. Ellis, New Zealand geochemist.

Properties of Ellisite

The following are the key properties of Ellisite:

  • Cell Data
    • Space Group: R3m (synthetic)
    • a = 12.324
    • c = 9.647
    • Z = 7.
  • Crystal Data
    • Hexagonal
    • Point Group: 3m (synthetic)
    • As anhedral to irregular grains, to 1.3 mm, some having rhombohedral form; also massive
    • X-ray Powder Pattern: 2.669 (100), 3.214 (53), 5.333 (37), 2.327 (28), 3.559 (20), 1.780 (15), 2.757 (10).
  • Chemical Composition
    Elements Content 1 Content 2
    Tl 78.2 78.18
    S 12.3 12.27
    As 9.6 9.55
    Total 100.1 100.00
  • Optical Properties
    • Anisotropism: From blue-purple to red-purple to brownish orange.
  • Estimated Properties
    Electron density Bulk density (electron density) = 5.93 g/cm3
    note: Specific gravity of Ellisite = 7.18 g/cm3
    Photoelectric PEEllisite = 1399.96 barns/electron
    U = PEEllisite x ρElectron density = 8305.21 barns/cm3
    Fermion index Fermion index = 0.00091
    Boson index = 0.99908

    Radioactivity

    Ellisite is not radioactive.

How to Identify Ellisite

Ellisite can be identified by its dark gray color, pale brown streak, metallic luster, perfect cleavage and opaque characteristics. It can be formed as rhombohedral crystals. The density of ellisite is 7.1 g/cm3, and its hardness is 2.

Global Distribution

Ellisite is widely distributed in the Carlin mine, 50 km northwest of Elko, Lynn district, Eureka Co., Nevada, USA.

Occurrence of Ellisite and Useful Mineral Association

Ellisite occurs in a hydrothermal gold deposit, in mineralized, argillaceous, and carbonaceous dolostone beds. It is closely associated with hydrocarbons, carlinite, arsenic, realgar, getchellite, lorandite, christite, pyrite and gold.

References

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