Tetradymite

sulphide

tellurium

Formula: Bi2Te2S
Sulphide, tetradymite group
Specific gravity:
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).

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, Québec, 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, Québec, 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).

The type locality is Župkov, Žarnovica county, Banská Bystrica Region, Slovakia.

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