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Formula: CaZn11(UO2)(CO3)3(OH)20.4H2O
Hydrated uranyl carbonate
Crystal System: Monoclinic
Specific gravity: 3.01 to 3.1 measured, 3.15 calculated
Streak: White
Colour: White to light yellow
Luminescence: Yellow-green fluorescence under short wave and under long wave UV from the Lill mine: not fluorescent
under UV from Mas d'Alary
Solubility: Readily soluble in acid, with evolution of CO2
Very strongly RADIOACTIVE
Environments
Znucalite is a rare secondary species at
carbonate-hosted polymetallic veins, and nearby oxidising uranium veins; on
dump material and coating mine walls, apparently of post-mine origin
HOM
Localities
At the type locality, the Lill Mine, Černojamské deposit, Březové Hory, Příbram, Příbram District, Central
Bohemian Region, Czech Republic, znucalite occurs as porous coatings of saucer-shaped aggregates, up to
10 cm2, some consisting of thin plates averaging 15 x 8 x 0.4 microns3. Colour white, light
yellow, greyish yellow, translucent, silky lustre. Associated minerals include
gypsum, hydrozincite,
aragonite, sphalerite,
galena, pyrite,
serpierite, römerite and
calcite. Znucalite occurs as an oxidation product on
uraninite-bearing dump material
(AM 76.1732-1733, HOM).
Znucalite from the Lill Mine -
IMage
At the Mas d'Alary opencast mine, Lodève, Lodève, Hérault, Occitanie, France, znucalite occurs as spherules
to 350 microns in diameter in the oxidation zone of the uranium deposit.
Associated minerals include adamite,
metalodevite, umohoite,
calcurmolite, uranophane
and studtite
(AM 79.1214, HOM).
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