Mercury selenide

Mercury selenide (HgSe; sometimes mercury(II) selenide) is a chemical compound of mercury and selenium. It is a grey-black crystalline solid semi-metal with a sphalerite structure. The lattice constant is 0.608 nm.

HgSe occurs naturally as the mineral Tiemannite, and is a component of the "intimate mixture" of HgSe and Se known as HgSe2.

Along with other II-VI compounds, colloidal nanocrystals of HgSe can be formed.

Applications

 * Selenium is used in filters in some steel plants to remove mercury from exhaust gases. The solid product formed is HgSe.
 * HgSe can be used as an ohmic contact to wide-gap II-VI semiconductors such as zinc selenide or zinc oxide.

Toxicity
Toxic hydrogen selenide fumes can be evolved on exposure to acids. HgSe is non-toxic as long as it is not ingested due to its insolubility.

HgSe is forms large insoluble clusters with proteins during digestion, and a very precise co-administration of selenium during mercury ingestion has shown to reduce the resulting intoxication. The effect is too finicky for any practical use, but selenium's ability to complex mercury has been proposed to explain why relatively high mercury levels do not intoxicate deep-sea fish.