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Formula: Cu6[Cu4(Fe,Zn)2]Sb4S13
"Tetrahedrite" was discredited as a species in 2019, and the name now refers to five minerals:
tetrahedrite-(Fe): Cu6(Cu4Fe2)Sb4S13
tetrahedrite-(Hg): Cu6(Cu4Hg2)Sb4S13
tetrahedrite-(Mn): Cu6(Cu4Mn2)Sb4S13
tetrahedrite-(Ni): Cu6(Cu4Ni2)Sb4S13
tetrahedrite-(Zn): Cu6(Cu4Zn2)Sb4S13
Sulphosalts, tetrahedrite group
Specific gravity: 4.6 to 5.2
Hardness: 3 to 4
Streak: Black
Colour: Steel grey to iron black
Solubility: Slightly soluble in nitric acid
Common impurities: Ag,Pb,Zn,Fe,As
Environments:
Pegmatites (rare)
Metamorphic environments
Hydrothermal environments (usual)
Tetrahedrite usually occurs in epithermal (low temperature) to
mesothermal (moderate temperature) hydrothermal veins, rarely in
pegmatites, and also in some
contact
metamorphic deposits of low to medium temperatute of formation. Associated minerals include
chalcopyrite, galena,
sphalerite, pyrite,
bornite, acanthite,
calcite, dolomite,
siderite, baryte,
fluorite and quartz
(HOM).
Localities
At Charcas, Charcas Municipality, San Luis Potosí, Mexico,
the primary minerals are
sphalerite, galena,
chalcopyrite, bornite,
>tetrahedrite,
arsenopyrite, pyrite and
silver minerals such as jalpaite,
diaphorite and acanthite. In
the host rock, as metamorphic or alteration minerals, danburite,
datolite, hedenbergite,
epidote, chlorite,
andradite, actinolite
and wollastonite have been reported.
Quartz, calcite and
danburite crystallised during the entire life of the systems, throughout
the intrusive emplacement, metamorphism, and mineralising events. With depth, both
sphalerite and galena decrease
while chalcopyrite increases.
Secondary sulphides formed include
bornite, covellite,
digenite and chalcocite.
Native silver, native gold,
hematite and goethite were
deposited after the sulphides
(Minrec 55.6.727-728).
Tetrahedrite has been found replacing pyrite,
sphalerite and chalcopyrite,
and is itself replaced by galena and occasionally by
bornite and covellite.
Tetrahedrite also occurs as dark, idiomorphic crystals to 1 cm. Close associations include
chalcopyrite, galena,
pyrite, danburite and
datolite
(Minrec 55.6.771-773).
At the Huanzala Mine, Huanzala, Huallanca District, Bolognesi Province, Ancash, Peru, specimens have been
found with plates of white calcite mixed with massive black
tetrahedrite, all completely covered by interlocked crystals of tetrahedrite,
galena and fluorite. The
galena appears as sharp, skeletal crystals to 2 cm, and the
fluorite as colourless, transparent, stepped octahedrons up to
2 cm in size, but the most specracular mineral is the tetrahedrite, which forms razor-sharp, lightly
striated, brilliant metallic black tetrahedral crystals to more than 2 cm in size
(MinRec 55.1.86).
Tetrahedrite from Huanzala - Image
From Herodsfoot Mine, Lanreath, Cornwall, England, UK, specimen BM.1964,R1021 from the Natural History Museum, London,
Features dull metallic grey tetrahedrite crystals with tristetrahedral modifications and an overgrowth of bright
brassy chalcopyrite, richly covering a matrix of milky
quartz veinstone
(RES2).
Tetrahedrite from Herodsfoot Mine - Image
At Redruth, Cornwall, England, UK, tetrahedrite has been found with
chalcopyrite and
calcite
(FM 47545).
At the Eagle Crag Mine, Patterdale, Eden, Cumbria, England, UK, sharp crystals of tetrahedite to 3 mm in size have
been found on a quartz matrix
(AESS).
Tetrahedrite from Eagle Crag - Image
At the Magma mine, Pioneer District, Pinal county, Arizona, USA, tetrahedrite has been found associated with
quartz
(R&M 95.1.88).
Alteration
chalcopyrite, stibnite and
sulphur to Fe-tetrahedrite and
pyrite
10 CuFeS2 + 2 Sb2S3 + 3/2 S2 →
Cu10Fe2As4S13
+ 8FeS2
(CM 28.725-738)
skinnerite and sphalerite =
Zn-tetrahedrite and chalcocite
4Cu3SbS3 + 2ZnS → Cu10Zn2Sb4S13 + Cu2S
(CM 28.725-738)
Fe-tetrahedrite, berthierite and
sulphur to chalcopyrite and
stibnite
Cu10Fe2Sb4S13 + 2FeSb2S4 + 11/2S2 →
10CuFeS2
+ 4Sb2S3
(CM 28.725-738)
Fe-tetrahedrite, siderite and
sulphur to chalcopyrite,
stibnite, CO2 and O2
Cu10Fe2Sb4S13 + 8Fe(CO3) + 13/2S2 → 10CuFeS2
+ 2Sb2S3 + 8CO2 + 4O2
(CM 28.725-738)
Zn-tetrahedrite to chalcocite,
antimony, sphalerite and
sulphur
Cu10Zn2Sb4S13 → 5Cu2S + 4Sb + 2ZnS + 3S2
(CM 28.725-738)
tetrahedrite
antimony, sphalerite and
sulphur
3Cu10Zn2Sb4S13 → 10Cu3SbS3 + 2Sb + 6ZnS +
3/2S2
(CM 28.725-738)
tetrahedrite
stibnite and sphalerite
3Cu10Zn2Sb4S13 → 10Cu3SbS3 +
Sb2S3 + 6ZnS
(CM 28.725-738)
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