Oswaldpeetersite

oswaldpeetersite

coconinoite

sklodowskite

mbobomkulite

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Formula: (UO2)2(CO3)(OH)2.4H2O
Carbonate, uranyl mineral
Crystal System: Monoclinic
Specific gravity: 4.1 to 4.55 measured, 4.54 calculated for the empirical formula and 4.50 calculated for the idealised formula
Hardness: 2 to 3
Streak: Pale yellow
Colour: Canary yellow
Luminescence: Does not fluoresce under 360 nm light
Solubility: Soluble with effervescence in dilute hydrochloric acid
Strongly RADIOACTIVE
Environments

Sedimentary environments

Localities

At the type locality, the Jomac Mine, White Canyon Mining District, San Juan County, Utah, USA, oswaldpeetersite occurs in conglomerate that is rich in organic material such as black coal-bearing smears and logs of partially petrified wood. Coconinoite is the most common U6+-bearing mineral at the mine and is found scattered throughout the conglomerate, locally replacing organic debris. Oswaldpeetersite occurs, associated with gypsum, along bedding planes of a layer of siltstones within the conglomerate. Additional associated minerals are cuprite, antlerite, goethite, lepidocrocite, mbobomkulite, hydrombobomkulite, sklodowskite and two undefined uranium minerals.
Oswaldpeetersite most commonly occurs as micrometric prismatic crystals arranged in radiating groups, rarely distributed on layers of gypsum. The dimensions of the crystals are approximately 0.1 x 0.01 x 0.002 mm3+ (CM 39.1685-1689).
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