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Formula: Bi2Te2S
Sulphide of bismuth and
tellurium,
tetradymite group
Crystal System: Trigonal
Specific gravity: 7.3 measured, 7.271 calculated
Hardness: 1½ to 2
Streak: Pale steel-grey
Colour: Bright steel-grey, tin-white, tarnishes iridescent to dull
Environments:
Metamorphic environments
Hydrothermal environments
Tetradymite is a bismuth tellurium sulphide found in hydrothermal quartz -
gold veins of moderate to high temperature and
contact metamorphic deposits (Webmin, HOM). Associated minerals include
tellurium, tellurobismuthite,
gold, silver,
bismuth, hessite,
petzite, calaverite,
matildite, altaite,
pyrite, pyrrhotite,
galena, sphalerite,
arsenopyrite, chalcopyrite and
quartz (HOM).
Localities
At Llallagua, Rafael Bustillo, Potosí, Bolivia, tetradymite is found as inclusions in
bismuthinite (MinRec 37.2.154).
At the Jumbo Mine, Rossland, British Columbia, Canada, tetradymite has been found together with
gold as a thin film on monzonite
(AM 34.371-372).
At the McKenzie Red Lake Gold Mines, Kenora District, Ontario, Canada, tetradymite has been found in a polished section with
galena
(AM 34.371-372).
At the Siscoe Gold Mines, Siscoe, Timiskaming District, Ontario, Canada, tetradymite has been found as a specimen of
tourmalinized quartz with small areas of
calcite with coarse gold rarely in contact with small
grains of tetradymite
(AM 34.371-372).
At the McKellar Longworth Mine, Schreiber, Thunder Bay District, Ontario, Canada, tetradymite has been found in a polished section
with chalcopyrite and gold
(AM 34.371-372).
At the Perron mine, Abitibi-Témiscamingue, Quebec, Canada, tetradymite has been found as several pieces of coarsely crystalline
calcite with films of bronzy tetradymite associated with
gold
(AM 34.371-372).
At the Powell Rouyn Mine, Abitibi-Témiscamingue, Quebec, Canada, tetradymite has been found as a somewhat decomposed stringer
of tetradymite in a pyritized quartzose rock coated on
two sides by chlorite, calcite crystals,
pyrite, and free gold
(AM 34.371-372).
At Sonora Gulch, Hayes Creek, Whitehorse mining district, Yukon, Canada, attractive nuggets containing about equal
amounts of
tetradymite and gold have been found
(R&M 96.3.209).
The type locality is Župkov, Žarnovica county, Banská Bystrica Region, Slovakia.
At the Golden Crest occurrence, Kokomo-Tenmile area, Summit county, Colorado, USA, small specimens containing both
tetradymite and native gold have been found
(R&M 96.3.209).
At the Sylvanite District, Hidalgo county, New Mexico, USA, tetradymite is an almost invariable associate of
native gold
(R&M 96.3.209).
At the Whitehall Mines, Gold-Pyrite Belt, Spotsylvania county, Virginia, USA, several
gold with
tetradymite specimens have been found
(R&M 96.3.209).
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