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Formula: Ba(UO2)3(Se4+O3)2O2.4H2O
Selenite, barium- and
uranyl- bearing mineral
Crystal System: Orthorhombic
Specific gravity: 4.88
Hardness: 2
Streak: Light yellow
Colour: Bright yellow
Luminescence: Not fluorescent
RADIOACTIVE
Environments
Localities
At the Shinkolobwe Mine, Shinkolobwe, Kambove Territory, Haut-Katanga, DR Congo, guilleminite has been
found occasionally associated with hydrated uranium oxides,
rutherfordine and
uranophane
(Lauf2).
At the type locality, the Musonoi mine, Kolwezi, Kolwezi mining district, Lualaba, DR Congo, guilleminite
occurs in the oxidised portions of a
uranium-selenium-copper deposit,
in cavities in selenian digenite.
Associated minerals include malachite,
cuprosklodowskite, kasolite,
marthozite, derriksite,
uranophane and wulfenite
(HOM, Mindat, Dana).
The guilleminite forms canary-yellow powdery to microcrystalline coatings, silky to fibrous masses and small
spherical nodules in cavities in the host rock. The crystals are typically opaque to translucent, rarely transparent
in very small crystals
(Lauf2).
Guilleminite from the Musonoi mine - Image
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