Tetrahedrite

minerals

chalcopyrite

stibnite

skinnerite

Formula: Cu6[Cu4(Fe,Zn)2]Sb4S13
"Tetrahedrite" was discredited as a species in 2019, and the name now refers to two end members,
tetrahedrite-(Fe): Cu6(Cu4Fe2)Sb4S13
tetrahedrite-(Zn): Cu6(Cu4Zn2)Sb4S13
Sulphosalts
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 Redruth, Cornwall, England, UK, tetrahedrite has been found with chalcopyrite and calcite (FM 47545).

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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