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Formula: (NH4)2(UO2)5(SeO3)3O2(OH)2(H2O).8H2O
Hydrated selenite, uranyl
mineral
Crystal system: Triclinic
Specific gravity: 4.178 calculated for both the empirical and ideal formulas
Hardness: 2
Streak: Pale yellow
Colour: Yellow
Solubility: Soluble in dilute hydrochloric acid at room temperature
Common impurities: Na,K
Environments
Sedimentary environments
Hydrothermal environments
Amurselite is an extremely rare mineral formed as a post-mining oxidation product in
sandstone-hosted
uranium-vanadium systems
(Mindat).
Localities
The Burro Mine, San Miguel County, Colorado, USA, is the type locality for amurselite and for 12 other
minerals: ammoniolasalite,
ammoniomathesiusite,
ammoniozippeite,
bobfinchite, burroite,
caseyite, metamunirite,
metauroxite,
nitroplumbite, okieite,
protocaseyite and uroxite.
At the mine uranium and vanadium
minerals occur together in deposits in sandstone. The
uranium and vanadium ore
mineralisation was deposited where solutions rich in uranium and
vanadium encountered pockets of strongly reducing solutions that had
developed around accumulations of carbonaceous plant material.
The uranium in amurselite was principally leached from
uraninite,
whereas the selenium may have been leached from weathered
clausthalite or
selenium-bearing covellite.
The NH4 in amurselite is likely sourced from organic material in the
sandstones. Amurselite is very rare, so far having been
found on only a few micromount samples. It occurs on asphaltite
with gypsum, natrozippeite,
quartz, and a potential new mineral that appears to correspond to synthetic
Li2(UO2)3(SeO3)2O2(H2O)6
Amurselite occurs as yellow prisms or blades up to about 0.1 mm in length, commonly forming divergent
intergrowths or compact balls
(CJMP 63.3.305-315).
Amurselite from the Burro Mine -
Image
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