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Formula: Ba(U6+O2)2(PO4)2.6H2O
Hydrated phosphate, uranyl mineral,
meta-autunite group. Rapid dehydration of
uranocircite in dry atmospheres at normal temperature results in
metauranocircite
(Mindat).
Specific gravity: 3.94
Hardness: 2 to 2½
Streak: Yellowish white
Colour: Greenish yellow, yellowish green
RADIOACTIVE
Environments
Pegmatites
Hydrothermal environments
Metauranocircite occurs typically as a secondary mineral
derived from phosphatic
uraninite deposits in the oxidised zone of some uranium deposits; it may be
primary in low-temperature veins, and it also occurs in
granite pegmatites. Associated minerals include
autunite,
coffinite, haiweeite,
meta-autunite,
metatorbernite,
metatyuyamunite,
metauranopilite,
phurcalite, torbernite,
uraninite, uranophane,
uranophane-β and zippeite group
minerals
(HOM, Webmin, Mindat).
Localities
The type locality is the Krunkelbach Valley Uranium deposit, Menzenschwand, St Blasien, Waldshut, Freiburg Region,
Baden-Württemberg, Germany.
Metauranocircite from Krunkelbach - Image
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