Natural Selenide

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Selenide, Natural

 

any of a group of mineral compounds that is a combination of selenium and metals. Approximately 30 selenide minerals are known. They are analogues of sulfides, with which they form common structural types of continuous or limited series of solid solutions. Unlike S, which forms minerals with more than 40 elements, Se combines with a relatively small number of elements: Pb [clausthalite (PbSe)], Hg [tiemannite (HgSe)], Bi [guanajuatite (Bi2 Se3)], Ag [naumannite (Ag2Se), aguilarite (Ag4SeS)], Cu [klockmannite (CuSe), berzelianite (Cu2Se), umangite (Cu3Se2)], Co [freboldite (CoSe)], Fe [ferroselite (FeSe2), achawalite (FeSe)], Ni [blockite (NiSe2)], Zn [shtilleite (ZnSe)], Cd [cadmoselite (CdSe)], and Tl. Examples of complex selenides are crookesite [(Cu3TlAg)2Se] and eucairite (CuAgSe).

Most selenides are rare. The largest commercial Se reserves, in relatively low concentrations, are associated with sulfide deposits, in which Se isomorphically replaces S in sulfide minerals. Selenide minerals proper are formed during hydrothermal processes under conditions marked by a sharply reduced potential of S. Hydrothermal selenide deposits are usually small but have a very high Se content (Pajacana in Bolivia and deposits in Argentina and the German Democratic Republic). There are also subvolcanic deposits, usually of gold ore, and deposits formed through hypergenesis with selenium mineralization.

REFERENCES

Sindeeva, N. D. Mineralogiia, tipy mestorozhdenii i osnovnye cherty geokhimii selena i tellura. Moscow, 1959.
Geokhimiia, mineralogiia i geneticheskie tipy mestorozhdenii redkikh elementov, vol. 1. Moscow, 1964.
Mineraly: Spravochnik, vol. 1. Moscow, 1960.

A. S. MARFUNIN

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
He stated that the paragenesis of native selenium is most widespread as a weathering product of natural selenides, especially clausthalite, where it is associated with cerussite and others (Ramdohr, 1937).