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Formula: BaV4+5V5+2O16.3H2O
Vanadate, barium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.24 measured, 3.256 calculated for the empirical formula, 3.301 calculated for the ideal formula
Hardness: 2½
Streak: Light greenish blue
Colour: Dark blue
Luminescence: Not fluorescent under UV
Sedimentary environments
Hydrothermal environments
Pandoraite-Ba is a relatively new mineral, approved in 2018 and to date (June 2023) reported only from the
type locality.
Localities
At the type locality, the Pandora mine, La Sal Mine, La Sal Mining District, San Juan County, Utah, USA, 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. Under ambient temperatures and generally oxidising
near-surface conditions, water reacts with pyrite and
chalcopyrite to form aqueous solutions with relatively low pH (acid),
which then react with earlier-formed
montroseite-corvusite
assemblages, resulting in diverse suites of secondary minerals.
Pandoraite-Ba and pandoraite-Ca are rare and occur on matrix
consisting of recrystallised quartz grains from the original
sandstone, that are intermixed with an unknown
iron-vanadium-oxide phase.
Well-formed crystals of carnotite and tiny plates of a
barium - iron -
vanadium
bearing member of the alunite supergroup are intimately associated with
pandoraite-Ba. The pandoraite minerals occur as thin, dark blue, square plates up to approximately 100
microns across and approximately 2 microns thick
(CM 57.255-265).
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