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Formula: Tl3AsS3
Valence: Tl1+3As3+S2-3
Sulpharsenite of thallium
Crystal system: Trigonal
Specific gravity: 7.10 measured on synthetic material, 7.18 calculated
Hardness: 2
Streak: Light brown with a tinge of orange
Colour: Dark grey
Environments
Sedimentary environments
Hydrothermal environments
Localities
At the type locality, the Carlin Gold mine, Elko, Lynn Mining District, Eureka County, Nevada, USA, ellisite
occurs in mineralised, laminated, argillaceous, carbonaceous dolomite
beds. Dispersed grains of ellisite are spatially associated with
lorándite, getchellite,
christite and realgar. Prior to
this last stage of mineralisation, hydrothermal quartz and
pyrite replaced calcite, and
kaolinite and sericite formed in
the matrix of the carbonate host rock. The rocks also contain veinlets, seams, and irregular patches, normal and
parallel to bedding planes in the laminated host rock, made up of ellisite, abundant
realgar and small amounts of
lorándite, christite and
getchellite.
Most of the grains of ellisite were anhedral to irregular, and ranged from about 0.5 to 1.3 mm in length;
several broken grains showed good rhombohedral shapes. Small grains enclosed by or intergrown with the assemblage of
lorándite, getchellite,
christite and realgar are about
0.4 to 1 mm in length, and grains of ellisite in the veinlets and patches, intergrown with other
arsenic minerals, range from about 0.2 to 0.5 mm in longest dimension.
Broken grains of ellisite display a deep red to deep orange-red internal reflection
(AM 64.701-707).
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