Tennantite

sulfosalt

tetrahedrite

Formula: Cu6[Cu4(Fe,Zn)2]As4S13
Sulfosalt, tetrahedrite group
Specific gravity: 4.6 to 4.7
Hardness: 4
Streak: Black
Colour: Black
Environments:

Sedimentary environments
Metamorphic environments
Hydrothermal environments

Tennantite is widely distributed in hydrothermal veins and contact metamorphic deposits, associated with pyrite, chalcopyrite, galena, acanthite, sternbergite, enargite, bornite, covellite, calcite, dolomite, siderite, baryte, fluorite and quartz (HOM, Dana, Mindat, Webmin, R&M 86.4.330).
Wormlike intergrowths with galena, stromeyerite, chalcocite, and pyrargyrite have been observed (R&M 86.4.330).
Pseudomorphs of tennantite after enargite are common. Pseudomorphs of pitticite, erythrite, malachite and azurite after tennantite have been reported (R&M 86.4.330).

In Bärndorf, Styria, Austria, tennantite is associated with tyrolite, dolomite and quartz (R&M 86.4.330).

At the Magnet Cove baryte mine, Nova Scotia, Canada, tennantite is associated with galena, chalcopyrite, gersdorffite, proustite and acanthite (R&M 86.4.330).

At Freiberg, Saxony, Germany, tennantite is associated with arsenopyrite, chalcopyrite and quartz (R&M 86.4.330).

At Hammerunterwiesenthal, Saxony, Germany, tennantite is associated with carminite, olivenite and chalcopyrite (R&M 86.4.330).

At the König David mine, Saxony, Germany, tennantite is associated with carminite and plumbogummite (R&M 86.4.330).

At the Pfannenberger Union mine, Westfalen, Germany, druses of microcrystals of tennantite on chalcopyrite have been found (R&M 86.4.330).

At Dzhezkazgan, Kazakhstan, tennantite is associated with chalcopyrite, bornite, chalcocite, galena, sphalerite variety cleiophane, arsenopyrite, betekhtinite, dolomite and calcite (R&M 86.4.330).

At Naica, Chihuahua, Mexico, tennantite is associated with chalcopyrite, sphalerite and pyrite (R&M 86.4.330).

At the El Cobre mine, Zacatecas State, Mexico, tennantite-tetrahedrite on milky quartz is associated with pyrite and sphalerite (R&M 86.4.330).

At Tsumeb, Namibia, tennantite is associated with mimetite, germanite, azurite, dolomite, calcite and aragonite. Tennantite coating cerussite and pseudomorphs of tennantite after azurite and chalcocite are also known from this locality (R&M 86.4.330).

At the Julcani district, Huancavelica department, Peru, tennantite is associated with baryte, and pseudomorphs of tennantite after enargite have been found (R&M 86.4.330).

In the Huaron district, Pasco department, Peru, tennantite is associated with quartz and pyrite (R&M 86.4.330).

At Wheal Jewel, Gwennap, Cornwall, UK, tennantite occurs encrusting chalcopyrite (R&M 86.4.330).

At the Freeland and Lamartine mines, Clear Creek county, Colorado, USA, tennantite occurs as overgrowths on chalcopyrite crystals, all on siderite, which has grown on a dense intergrowth of pyrite, sphalerite, chalcopyrite and quartz (R&M 87.4.304-336) .

Near Idaho Springs, Clear Creek county, Colorado, USA, tennantite crystals form around cores composed of chalcopyrite, and are associated with siderite, pyrite and quartz (R&M 86.4.330).

In the Rico district, Dolores county, Colorado, USA, tennantite is associated with chalcopyrite and pearceite (R&M 87.4.304-336).

At Central City, Gilpin county, Colorado, USA, tennantite is associated with chalcopyrite, quartz, pyrite and sphalerite, with the tennantite often epitaxial on chalcopyrite. This epitaxial growth is also found at the Saratoga and Notaway mines in Russell Gulch, also in Gilpin county (R&M 87.4.304-336).

In the Bonanza District, Saguache county, Colorado, USA, tennantite has been reported associated with chalcopyrite and bornite in vugs in ore (R&M 87.4.304-336).

At the Yankee Girl mine, San Juan county, Colorado, USA, tennantite has been found associated with rhodochrosite, stromeyerite and miargyrite (R&M 86.4.330).

In the Georgetown district, Bear Creek county, Idaho, USA, tennantite is associated with chalcocite, pyrite, calcite and quartz (R&M 86.4.330).

At Butte, Silver Bow county, Montana, USA, tennantite is associated with chalcopyrite, enargite, bornite, rhodochrosite and quartz. Also tennantite pseudomorphs after enargite have been found here (R&M 86.4.330).

At the Carlin mine, Eureka county, Nevada, USA, tennantite pseudomorphs after sphalerite have been found in baryte veins (R&M 86.4.330).

At the Monitor mine, White Pine county, Nevada, USA, tennantite is associated with enargite, bournonite, andorite and quartz (R&M 86.4.330).

Alteration

chalcopyrite, arsenopyrite, CO2 and O2 to Fe-tennantite, siderite and sulphur
10CuFeS2 + 4FeAsS + 4CO2 + 8O2 → Cu10Fe2As4S13 + 4Fe(CO3) + 11/2S2
(CM 28.725-738)

chalcopyrite, arsenopyrite and pyrite to Fe-tennantite and troilite
10CuFeS2 + 4FeAsS + FeS2 → Cu10Fe2As4S13 + 13FeS
(CM 28.725-738)

chalcopyrite, arsenopyrite and sulphur to Fe-tennantite and pyrite
10CuFeS2 + 4FeAsS + 13/2S2 → Cu10Fe2As4S13 + 12FeS2
This reaction occurs at a comparatively low temperature (CM 28.725-738).

chalcopyrite, arsenopyrite and sulphur to Fe-tennantite and troilite
l0CuFeS2 + 4FeAsS + l/2S2 → Cu10Fe2As4S13 + l2FeS
(CM 28.725-738)

enargite and pyrite to Fe-tennantite, chalcopyrite and sulphur
4Cu3AsS4 + 4FeS2 → Cu10Fe2As4S13 + 2CuFeS2 + 7/2S2
(CM 28.725-738)

Common impurities: Sb,Bi,Pb

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