Freibergite

Formula: Ag₆[Cu₄Fe₂]Sb₄S₁₂
Discredited as a mineral species. Now considered to be a subgroup including argentotetrahedrite-(Fe).
Sulphosalt, tetrahedrite group, forms a series with tetrahedrite and with argentotennantite
Specific gravity: 5.1
Hardness: 4
Streak: Reddish black
Colour: Grey to black
Common impurities: Zn,Hg,Bi
Environments:

Hydrothermal environments

Freibergite is a antimony-bearing mineral that occurs in hydrothermal deposits associated with a wide variety of sulphides and sulphosalts (HOM)

The type locality is the Reiche Zeche Mine, Himmelfahrt Mine, Freiberg, Mittelsachsen, Saxony, Germany.

At Yaogangxian, Yizhang county, Chenzhou, Hunan, China, a very few samples of freibergite have been found on bournonite (Minrec 42.6.581-586).

At the Guerro and San Antonio mines, Taxco de Alarcon, Mexico, freibergite has been found as inclusions in chalcopyrite filling vugs in pyrite and galena (Minrec 42.5.429).

At the Imiter Mine, Tinghir Province, Drâa-Tafilalet, Morocco, freibergite occurs rarely in dolomite veins as crystals containing traces of mercury and associated with cinnabar (Minrec 42.2.123).

At the Eagle mine, Eagle county, Gilman district, Colorado, USA, freibergite has been found as alterations of, and fine grained crystalline coatings on, chalcoprite and tetrahedrite (R&M 87.4.318).

At the Eldorado Mine, Yankeeboy basin, Ouray county, Colorado, USA, freibergite occurrs rarely associated with sphalerite on crystallised dolomite (R&M 84.5.423).

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