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Formula: Cu6[Cu4(Fe,Zn)2]As4S13
"Tennantite" was discredited as a species in 2019, and the name now refers to seven minerals:
tennantite-(Cd): Cu6(Cu4Cd2)As4S13
tennantite-(Cu): Cu6(Cu4Cu2)As4S13
tennantite-(Fe): Cu6(Cu4Fe2)As4S13
tennantite-(Hg): Cu6(Cu4Hg2)As4S13
tennantite-(Mn): Cu6(Cu4Mn2)As4S13
tennantite-(Ni): Cu6(Cu4Ni2)As4S13
tennantite-(Zn): Cu6(Cu4Zn2)As4S13
Sulpharsenite,
tetrahedrite group
Crystal System: Isometric
Specific gravity: 4.6 to 4.7
Hardness: 4
Streak: Black
Colour: Black
Common impurities: Sb,Bi,Pb
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).
Localities
In Bärndorf, Styria, Austria, tennantite is associated with tyrolite,
dolomite and quartz
(R&M 86.4.330).
Tennantite from Bärndorf - Image
At the Magnet Cove baryte mine, Nova Scotia, Canada, tennantite is associated with
galena,
chalcopyrite, gersdorffite,
proustite
and acanthite
(R&M 86.4.330).
Tennantite from Nova Scotia - Image
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 the Monte Cervandone area, Devero Alp, Baceno, Verbano-Cusio-Ossola Province, Piedmont, Italy, tennantite
appears to be the primary arsenic source, and was the first
arsenic sulphide found in the area. It occurs only as small
grains and masses in veins in the gneiss, associated with
quartz, and very rarely in sharp modified-tetrahedral crystals to 5 mm.
Typically it shows partial oxidation to malachite and/or
azurite. Presumably, tennantite is the source of the
arsenic that was then remobilised to form the interesting suite of
arsenic species on Monte Cervandone
(MinRec 56.3.318-319).
At Dzhezkazgan, Kazakhstan, tennantite is associated with chalcopyrite,
bornite, chalcocite,
galena, sphalerite variety cleiophane,
arsenopyrite, betekhtinite,
dolomite and calcite
(R&M 86.4.330).
Tennantite from Dzhezkazgan - Image
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).
Tennantite from Zacatecas -
Image
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, KL p135).
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, KL p136).
Tennantite from Julcani - Image
In the Huarón district, Pasco department, Peru, tennantite is associated with
quartz and
pyrite
(R&M 86.4.330).
Tennantite from Huarón - Image
At Wheal Jewel, Gwennap, Cornwall, England, UK, tennantite occurs encrusting
chalcopyrite
(R&M 86.4.330).
Tennantite from Wheal Jewel -
Image
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).
Tennantite from the Freeland Mine -
Image
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).
Tennantite from Central City -
Image
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).
Tennantite from Butte - Image
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 tennantite-(Fe), siderite and
sulphur
10CuFeS2 + 4FeAsS + 4CO2 + 8O2 → Cu10Fe2As4S13 +
4Fe(CO3) + 11/2S2
(CM 28.725-738)
chalcopyrite, arsenopyrite and
pyrite to tennantite-(Fe) and
troilite
10CuFeS2 + 4FeAsS + FeS2 → Cu10Fe2As4S13 + 13FeS
(CM 28.725-738)
chalcopyrite, arsenopyrite and
sulphur to tennantite-(Fe) 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 tennantite-(Fe) and
troilite
l0CuFeS2 + 4FeAsS + l/2S2 → Cu10Fe2As4S13 + l2FeS
(CM 28.725-738)
enargite and pyrite to
tennantite-(Fe), chalcopyrite and
sulphur
4Cu3AsS4 + 4FeS2 → Cu10Fe2As4S13 + 2CuFeS2
+ 7/2S2
(CM 28.725-738)
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