NMR properties:

Magnetogyric Ratio NMR frequency Natural abundance (NA) Nuclear spin (I) Quadrupole moment (Q) Reference sample
79 Se -1.39310^7 rad/sT 7.5 80fm²
79 Se

(Gr. Selene, moon) Discovered by Berzelius in 1817, who found it associated with tellurium, named for
the earth.
Selenium is found in a few rare minerals such as crooksite and clausthalite. In years past it has been
obtained from flue dusts remaining from processing copper sulfide ores, but the anode metal from
electrolytic copper refineries now provide the source of most of the world's selenium. Selenium is
recovered by roasting the muds with soda or sulfuric acid, or by smelting them with soda and niter.
Selenium exists in several allotropic forms. Three are generally recognized, but as many as that have
been claimed. Selenium can be prepared with either an amorphous or crystalline structure. The color of
amorphous selenium is either red, in powder form, or black, in vitreous form. Crystalline monoclinic
selenium is a deep red; crystalline hexagonal selenium, the most stable variety, is a metallic gray.
Selenium exhibits both photovoltaic action, where light is converted directly into electricity, and
photoconductive action, where the electrical resistance decreases with increased illumination. These
properties make selenium useful in the production of photocells and exposure meters for photographic
use, as well as solar cells. Selenium is also able to convert a.c. electricity to d.c., and is extensively used
in rectifiers. Below its melting point selenium is a p-type semiconductor and is finding many uses in
electronic and solid-state applications.
Elemental selenium has been said to be practically nontoxic and is considered to be an essential trace
element; however, hydrogen selenide and other selenium compounds are extremely toxic, and resemble
arsenic in their physiological reactions.