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
- 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
- Optical Properties
- Anisotropism: From blue-purple to red-purple to brownish orange.
- Estimated Properties
||Bulk density (electron density) = 5.93 g/cm3
note: Specific gravity of Ellisite = 7.18 g/cm3
||PEEllisite = 1399.96 barns/electron
U = PEEllisite x ρElectron density = 8305.21 barns/cm3
||Fermion index = 0.00091
Boson index = 0.99908
|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.
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.