Znucalite

znucalite

uraninite

serpierite

romerite

Images

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

Hydrothermal 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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