Empressite

Empressite is a mineral form of silver telluride, AgTe.It is a rare, grey, hexagonal crystal with which can form aggregates of bipyrimidal crystals. Twins do not form. Density 7600 kg.m^-3.

Recent crystallographic analysis [L. Bindi "et al.", American Mineralogist, 89, 1043 (2004)] has confirmed that empressite is a distinct mineral with orthorhombic crystal structure, different from the hexagonal Ag_5-xTe₃ with which empressite has been commonly confused in mineralogy literature. At the same time, empressite does not appear on the equilibrium Ag-Te phase diagram [Karakaya, I., Thompson, W.T.: J. Phase Equilibria 12, 56 (1991).] , and therefore it is only metastable at ambient conditions. Given infinite time, it would phase separate into pure Ag₅Te₃ and pure Te.

The name empressite comes from the location of its discovery – the Empress Josephine mine, Saguache County, Colorado, USA.

References

External links

* [http://www.webmineral.com/data/Empressite.shtml webmineral.com] entry
* [http://www.mindat.org/min-1379.html mindat.org] entry