Discovered by J. J. Berzelius at Stockholm, Sweden.
Remarks
Obtained as a silvery metallic allotrope or red
amorphous powder, which is less stable. Burns in air, unaffected by water, dissolves in
concentrated nitric acid and alkalies. Used in photoelectric cells, photocopier drums, solar cells, and semiconductors.
Diagnostic tests: Native Se and Se2-: Selenium and selenides are detected by heating the powdered mineral
on charcoal and are detected by a very pronounced smell described as
radishes or rotting radishes.
If the selenium is present in quantities, the blowpipe
test evolves a brownish smoke which deposits a silvery coating of
SeO2 near the assay. If this coating is touched with the reducing flame,
an azure-blue color is evident.
The open tube test, selenium yields a white oxide which
crystallizes in radiating prisms on the sides, often tinged with reddish
selenium. The coating is volatile and will advance depending on the
location of the flame.
The closed tube test, selenium volatizes and condenses
as black globules fused on the inside of the glass which may have a
reddish tint in the thinnest portion of the sublimate.
Selenates (SeO4)2- and
Selenites (SeO3)2-: Fuse a sample on charcoal
mixed with with soda (Na2CO3) and charcoal dust in
the reducing flame of the blowpipe. The reduction of SeO4 or
SeO3 is detected by the radish odor.
The azure blue seleniumflame
test color may be noticeable.
References
Emsley, J., 1991; THE ELEMENTS : Sec. Ed.,
Clarendon Press, Oxford, 251 p.
(* - Mineral Name Is Not IMA Approved)
(! - New Dana classification added or changed from Danas New Mineralogy)
(? - IMA Discredited Mineral Species Name)
There are 127 minerals with Se in the Mineralogy Database.