Freibergite is a sulfide that is complex composed of silver, copper, iron, antimony and arsenic. It forms a remedy that is solid with Tetrahedrite and another with Argentotennantite. Freibergite is opaque black with a luster that is metallic produces very attractive gems.

Freibergite is found at a genuine wide range of localities worldwide. In Germany, in Saxony, from the Freiberg region [TL], as in the Himmelsfürst mine, Erbisdorf, near Freiberg. From Kutná Hora together with 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 area, 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 within the Meerschaum mine, north of Omeo, Victoria. Additional localities are known.

Category: Sulfosalt minerals
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


Crystallography: Isometric – Hextetrahedral
Crystal Habit: Tetrahedral crystals, to 3.5 cm; massive and as inclusions in other sulfides.
Twinning: None


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


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