Dumontite

dumontite

torbernite

kasolite

uranophane

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Formula: Pb₂(UO₂)₃O₂(PO₄)₂.5H₂O
Hydrated phosphate containing hydroxyl, phosphuranylite group
Crystal System: Monoclinic
Specific gravity: 5.65 measured, 5.666 calculated
Hardness: 2 to 3
Streak: Light yellow
Colour: Golden yellow to ochre yellow
Solubility: Soluble in acids
Dehydration: H₂O is entirely lost by 300^oC (Dana )
RADIOACTIVE
Environments

Sedimentary environments
Hydrothermal environments

Dumontite is a secondary uranium mineral (Mindat, Webmin).

Localities

At the type locality, the Shinkolobwe mine, Kambove District, Haut-Katanga, DR Congo, dumontite is found in pockets in torbernite in the oxidised zone of a uranium deposit (Mindat, AM 10.131, HOM), associated with torbernite (Mindat, HOM).

Near Nogales, Arizona, USA, dumontite is associated with uranophane, kasolite and autunite (HOM).

At Goodsprings, Nevada, USA, dumontite is associated with kasolite (HOM).

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