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Formula: Na4(UO2)(SO4)3.3H2O
Valence: Na4(U6+O2)(S6+O4)3.3H2O
Hydrated uranyl sulphate
Crystal System: Orthorhombic
Specific gravity: 3.23 measured, 3.313 calculated
Hardness: 2½
Streak: White
Colour: Pale greenish yellow
Luminescence: Bright greenish white fluorescence under UV
Solubility: Slightly deliquescent and easily soluble in water at room temperature
Environments
Sedimentary environments
Hydrothermal environments
Fermiite was approved in 2014, but to date (June 2026) it has been reported only from the Red Canyon Mining
district (2 localities).
Localities
At the type locality, the Blue Lizard Mine, Red Canyon Mining District, San Juan County, Utah, USA, fermiite
and oppenheimerite occur together as
secondary alteration phases in association with
blödite, bluelizardite,
chalcanthite, epsomite,
gypsum, hexahydrite,
kröhnkite, manganoblödite,
sideronatrite, tamarugite
and wetherillite.
Fermiite occurs as pale greenish-yellow prisms, transparent with a vitreous lustre
(MM 79.5.1123-1142).
fermiite forms from post-mining oxidation of primary
uraninite, pyrite,
chalcopyrite, bornite and
covellite deposited as replacement of wood and other organic material,
and as disseminations in the enclosing sandstone
(HOM).
Fermiite from the Blue Lizard Mine -
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