Ferroselite

Infobox mineral
name = Ferroselite
category = Selenide mineral
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formula = FeSe₂
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color = Steel-gray to tin-white with a rose tint, brass yellow
habit = Acicular prismatic
system = Orthorhombic
twinning = Stellate and cruciform twins common
cleavage =
fracture =
mohs = 6 - 6.5
luster = Metallic
refractive = Opaque
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birefringence =
pleochroism = Distinct
streak = Black
gravity = 7.20
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solubility = insoluble in water
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references = [http://webmineral.com/data/Ferroselite.shtml Webmineral] http://www.mindat.org/min-1527.html Mindat.org] [http://rruff.geo.arizona.edu/doclib/hom/ferroselite.pdf Handbook of Mineralogy]

Ferroselite is an iron selenide of general formula FeSe₂ precipitated under reducing conditions in anoxic environments. It is a source of selenium in the Rocky Mountains where selenium occurrence is associated with Upper Cretaceous shale deposits.

It was first reported in 1955 for an occurrence in the Ust’-Uyuk uranium deposit in Tuva, Siberia.

In the frame of safety assessment calculations made for deep disposal of high-level radioactive waste, Ferroselite is also considered in geochemical calculations as one of the mineral phases limiting the solubility of Selenium-79.Fact|date=September 2008

References