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Argyrodite



Argyrodite
CategoryMineral
Chemical formulasilver germanium sulfide:Ag8GeS6
Identification
ColorBlack, purplish tinge
Crystal habittetrahedron or rhombic dodecahedron
Crystal systemOrthorhombic
Cleavageabsent
FractureConchoidal
Mohs Scale hardness2.5
Lustermetallic
Refractive indexopaque
Specific gravity6.2-6.5

Argyrodite, silver germanium sulfide Ag8GeS6 is relatively scarce mineral. The colour is iron-black with a purplish tinge, and the lustre metallic.

Discovered by Clemens Winkler in 1886 it is of interest as it was described shortly after the element germanium was isolated, 15 years after it had been postulated by Mendeleev. It occurs in the Himmelsfurst Mine, Freiberg, Saxony and in Bolivia.

It is of interest to note that the Freiberg mineral was long ago imperfectly described by August Breithaupt under the name Plusinglanz, and that the Bolivian crystals were incorrectly described in 1849 as crystallized brongniardite.

Isomorphous with argyrodite is the corresponding tin bearing mineral Ag8SnS6, also found in Bolivia as pseudocubic crystals, and known by the name canfieldite. There is also a related mineral, putzite, with composition (Cu4.7Ag3.3)GeS6.

Argyrodite gets its name from the Greek words that loosely translate into "rich in silver".

References

  • MinDat
  • Mineral Galleries: Argyrodite

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Argyrodite". A list of authors is available in Wikipedia.
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