Argyrodite
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| Argyrodite | |
|---|---|
| Category | Mineral |
| Chemical formula | silver germanium sulfide:Ag8GeS6 |
| Identification | |
| Color | Black, purplish tinge |
| Crystal habit | tetrahedron or rhombic dodecahedron |
| Crystal system | Orthorhombic |
| Cleavage | absent |
| Fracture | Conchoidal |
| Mohs Scale hardness | 2.5 |
| Luster | metallic |
| Refractive index | opaque |
| Specific gravity | 6.2-6.5 |
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".
[edit] References
This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
