Freibergite
Freibergite group
Rare · Ag₆(Cu₄Fe₂)Sb₄S₁₃₋ₓ
The silver-rich fahlore of the Freiberg silver mines in Saxony, named in 1853. The name was long used loosely for any silver-rich tetrahedrite; since the 2020 nomenclature of the tetrahedrite group it is a series name, the Freiberg mineral itself being kenoargentotetrahedrite-(Fe), with argentotetrahedrite-(Fe) beside it.
Identity
- Formula
- Ag₆(Cu₄Fe₂)Sb₄S₁₃₋ₓ
- Chemical class
- Sulfide
- Members
- Kenoargentotetrahedrite-(Fe), Argentotetrahedrite-(Fe)
- Also known as
- Silver fahlore, Argentian tetrahedrite
- Ore of
- Silver
Crystallography
- Crystal system
- Cubic
- Habits
- Pyramidal, Massive, Granular
- Fracture
- Uneven
Physical properties
- Mohs hardness
- 4
- Density
- 5 g/cm³
- Luster
- Metallic
- Colors
- steel gray, black
- Streak
- reddish black
- Transparency
- Opaque
Geology
- Origins
- Hydrothermal
- Host rocks
- Granite
- Associated minerals
- Tetrahedrite, Galena, Sphalerite, Pyrargyrite, Acanthite, Quartz
- Found in
- Hydrothermal vein (lode)
- Geography
- Germany (Himmelsfürst mine, Freiberg, Saxony), Czech Republic (Kutná Hora), Canada (Keno Hill, Yukon), Bolivia (San José mine, Oruro), Australia (Mount Isa, Cannington)
Classification
- Rarity
- Rare
- Gem quality
- No
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- C. Biagioni, L. L. George, N. J. Cook, E. Makovicky, Y. Moëlo, M. Pasero, J. Sejkora, C. J. Stanley, M. D. Welch, F. Bosi, The tetrahedrite group: Nomenclature and classification. American Mineralogist 105, 109–122, 2020.
- K. Qu and others, Kenoargentotetrahedrite-(Zn), [Ag₆]⁴⁺(Cu₄Zn₂)Sb₄S₁₂□, a new member of the tetrahedrite group from the Yindongpo Au deposit, China. European Journal of Mineralogy 36, 397–409, 2024.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Freibergite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Freibergite. Wikipedia.
- Freibergite Subgroup: Mineral information, data and localities. mindat.org.
- Argentotetrahedrite-(Fe): Mineral information, data and localities. mindat.org.
- Argentotetrahedrite-(Fe). Mineralogical Society of America, Handbook of Mineralogy (revised 2020).
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