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Formula: Ca2 (NH4)2 (V10O28).15H2 O
Decavanadate
Crystal System: Triclinic
Specific gravity: 2.43 measured
Hardness: 1½ to 2
Streak: Yellow
Colour: Orange-yellow
Luminescence: Not fluorescent under UV
Solubility: At room temperature, burroite is very slowly soluble in water and rapidly soluble in dilute
hydrochloric acid
Environments
Sedimentary environments
Hydrothermal environments
Burroite is relatively new mineral, approved in 2016 and to date (October 2022) reported only from the type locality.
Localities
At the type locality, the Burro Mine, Slick Rock Mining District, San Miguel County, Colorado, USA, U6+ and
V4+ were transported as dissolved species in weakly alkaline, moderately reducing CO2--rich groundwater,
and, upon encountering more reducing conditions by contacting carbonaceous material and H2S, were deposited as
uraninite and montroseite. Subsequent
exposure of those minerals to near-surface solutions, which had reacted with sulphide minerals and become more acidic, resulted
in the crystallisation of numerous secondary phases, including
burroite.
Burroite is very rare; it occurs as orange-yellow, somewhat flattened prisms up to 2 mm in length on
montroseite- and corvusite- bearing
sandstone in an apparently NH4-rich
secondary assemblage that also contains the NH4-bearing
decavanadates schindlerite and
wernerbaurite. Other
secondary minerals found in the mine include
barnesite, gypsum,
hewettite, magnesiopascoite,
metamunirite, metarossite,
navajoite, pascoite,
rossite and sherwoodite.
Burroite forms from the oxidation of
montroseite-corvusite assemblages in a
moist environment. The NH4 presumably derives from organic matter in the deposit
(CM 55.473-481).
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