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Formula: Ca(VO)2(AsO4)2.4H2O
Hydrated vanadyl arsenate
Crystal System: Triclinic
Specific gravity: 3.12 measured, 3.264 calculated for the empirical formula and 3.272 for the ideal formula.
Hardness: 2½
Streak: Colourless to pale green
Colour: Shades of light green
Luminescence: Not fluorescent under UV
Solubility: Insoluble in concentrated hydrochloric acid and in concentrated NaOH(aq) at room temperature
Environments
Sedimentary environments
Hydrothermal environments
Fulbrightite is a relatively new mineral, approved in 2019.
Localities
At the Geister vein, Rovnost Mine, Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic,
fulbrightite is a low-temperature secondary mineral,
closely associated with köttigite and
zeunerite; the general assemblage includes
babánekite, hloušekite and
crusts of poorly crystalline tyuyamunite -
metatyuyamunite. At the Rovnost mine, fulbrightite has been
observed only in greyish green to grey colours
(CM 58.5.663-671).
At the type locality, the Packrat Mine, Beaver Mesa, Gateway Mining District, Mesa County, Colorado, USA,
fulbrightite occurs on montroseite- and
corvusite- bearing
sandstone, closely associated with
pascoite, pharmacolite,
gatewayite, morrisonite,
packratite and vanarsite. The
fulbrightite forms from the oxidation of montroseite -
corvusite assemblages in a moist environment. Mining operations have
exposed unoxidised and oxidised phases. Under ambient temperatures and generally oxidising nearsurface conditions,
water reacts with pyrite and an unknown
arsenic-bearing phase (perhaps
arsenopyrite) to form aqueous solutions with relatively low pH (very
acid).
Crystals of fulbrightiteare square plates up to 0.5 mm across. Subparallel intergrowths of plates are
commonly grouped in rosettes in varying shades of green and brown, including lime-green, leek-green, olive-green,
green-brown and yellow-brown
(CM 58.5.663-671).
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