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Formula: (K,U,◻)(UO2)3(AsO4)(OH)4.H2O
Valence: K(U6+O2)3As5+O4(OH)4.H2O
Hydrated uranyl arsenate
Crystal system: Orthorhombic
Specific gravity: 5.45 to 5.65 measured
Hardness: 2
Streak: Yellowish
Colour: Yellow
Luminescence: No fluorescence under UV
RADIOACTIVE
Environments
Plutonic igneous environments
Hydrothermal environments
Localities
At the type locality, the Krunkelbach Valley Uranium deposit, Menzenschwand, St Blasien, Waldshut, Freiburg Region,
Baden-Württemberg, Germany, nielsbohrite belongs to the
secondary mineral assemblage of the oxidised
uranium deposit. It is associated with
hematite, pyrite,
schoepite, metazeunerite and
the gangue minerals quartz and
baryte. Nielsbohrite occurs mainly in euhedral rhombohedron-like crystals
reaching 0.15 mm in size. The mineral is yellow with a vitreous to dull lustre and with a yellowish streak
(EJM 21.2.515-520).
Nielsbohrite from the Krunkelbach Valley Uranium
deposit - Image
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