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Formula: TlHgAsS3
Valence: Tl1+Hg2+As3+S2-3
Sulphosalt, thallium-bearing mineral
Crystal System: Orthorhombic
Specific gravity: 6.2 measured on synthetic material, 6.37 calculated
Hardness: 1 to 2
Streak: Bright orange
Colour: Bright orange to deep red or crimson
Environments
Localities
At the Lanmuchang Tl deposit, Huijiabao gold field, Xingren County, Qianxinan, Guizhou, China, christite has
been found in thallium-rich pods in the stratabound
mercury deposit. Associated minerals include
lorandite, baryte,
marcasite and pyrite
(HOM).
At the type locality, the Carlin Gold mine, Elko, Lynn Mining District, Eureka County, Nevada, USA, christite
has been found in two areas in the deposit, with somewhat different mineral associations and host materials:
(1) Small isolated euhedral to subhedral crystals of christite occur intergrown with
lorandite, realgar and
orpiment between platy crystals of
baryte in small cavities and open spaces along the margins of
baryte veinlets. The christite occurs in subhedral grains varying from
about 0.5 mm to 1 mm in length, usually bounded by grains of realgar and
lorandite, and the grains also occur surrounded by or locked within
orpiment crystals.
(2)Christite occurs as small anhedral grains up to 0.25 mm across intergrown with abundant
realgar and small amounts of
lorandite, getchellite and
ellisite, in small veinlets filling microfractures and in small seams and
patches along bedding planes in mineralised silty carbonaceous
dolomite beds.
Other primary
thallium-bearing minerals of hydrothermal origin found at the Carlin deposit
include thallium-bearing orpiment,
lorandite, carlinite,
weissbergite and ellisite. In
oxidised zones the secondary mineral
avicennite has been found.
During the main period of hydrothermal activity, arsenic,
antimony and thallium were
deposited on surfaces of pyrite grains;
gold and mercury were also deposited on
pyrite and combined with carbonaceous materials to form various
gold and
gold-mercury organic compounds. It is
suggested that the veinlets formed during late-stage hydrothermal activity.
Christite is deep red or crimson in colour and is darker than realgar.
Thin plates and small crystals are red-orange to bright orange in colour; the streak is bright orange and the lustre
is adamantine. The colour in transmitted light ranges from deep red to orange in thick grains, to deep orange,
yellow-orange and yellow in successively thinner plates. Very strong brilliant red-orange internal reflections are
observed
(AM 62.421-425).
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