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Freibergite
Current inventory:  0 gems
 

  
Freibergite is named after the type locality of Freiberg, Saxony, Germany.

Discovered in 1853;   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

(Ag,Cu, Fe)₁₂(Sb, As)₄S₁₃

Silver Copper Iron Antimony Sulfide

Molecular Weight:

1929.46 gm

Composition:

Iron

3.47 %

Fe

Copper

11.86 %

Cu

Silver

40.25 %

Ag

Antimony

18.93 %

Sb

Arsenic

3.88 %

As

Sulfur

21.60 %

S

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Sulfides

Strunz 8th Ed. ID:

2/C.11-50

Nickel-Strunz 10th Ed. ID:

2.GB.05

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
G : Sulfarsenites, sulfantimonites, sulfbismuthites
B : Neso-sulfarsenites, etc. with additional S

Related to:

Tetrahedrite Group. Argentotennanite-Freibergite Series. Freibergite-Tetrahedrite Series. The Ag-dominant analogue of Tetrahedrite.

Varieties:

None

Synonyms:

Aphtonite, Leukargyrite, Weisgylden

Crystal Data

Crystallography:

Isometric - Hextetrahedral

Crystal Habit:

Tetrahedral crystals, to 3.5 cm; massive and as inclusions in other sulfides.

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

3.5 - 4.0; VHN₁₀₀=263 - 340 kg/mm²

Density:

4.85 - 5.41 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Gray, Steel Gray, Black

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

R: (400) 34.1, (420) 34.0, (440) 33.9, (460) 33.7, (480) 33.6, (500) 33.5, (520) 33.3, (540) 33.1, (560) 32.7, (580) 32.2, (600) 31.5, (620) 31.0, (640) 30.4, (660) 30.0, (680) 29.5, (700) 29.0

Birefringence:

0.00 (opaque)

Pleochroism:

None

Occurances

Geological Setting:

In hydrothermal deposits.

Common Associations:

A wide variety of sulfides and sulfosalts, as for tetrahedrite.

Common Impurities:

Zn, Hg, Bi

Type Locality:

Reiche Zeche Mine, Himmelfahrt Mine, Freiberg, Freiberg District, Erzgebirge, Saxony, Germany

Year Discovered:

1853

View mineral photos:

Freibergite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Freibergite is a complex sulfide mineral consisting of silver, copper, iron, antimony and arsenic. It forms a solid solution series with Tetrahedrite and another with Argentotennantite. Freibergite is opaque black with a metallic luster that makes for very attractive gems.

Freibergite is found at a number of localities worldwide. In Germany, in Saxony, from the Freiberg district [TL], as in the Himmelsfürst mine, Erbisdorf, near Freiberg. From Kutná Hora and the Zlate Hore district, Czech Republic. In Austria, from the Knappenstube mine, Hochtor, Salzburg. From Yukhondzha, Sakha, Russia. At Slädekärr and in the Vena mines, near Askersund, Örebro, Sweden. From the Bleikvassli Zn–Pb–Cu deposit, Nordland, Norway. In Scotland, at Tyndrum, Perthshire. In the Hi-Ho mine, Cobalt-Gowganda region, Ontario; and the Keno Hill-Galena Hill area, Yukon Territory, Canada. Large crystals from the San José mine, Oruro, Bolivia. In Japan, in the Inakuraishi, Koryu, and Sanru mines, Hokkaido. In Australia, at Mt. Isa and the Cannington Ag–Pb–Zn deposit, Queensland; and in the Meerschaum mine, north of Omeo, Victoria. Additional localities are known.
 

  
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