Dumontite
Dumontite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Pb₂(UO₂)₃O₂(PO₄)₂·5H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/m).
Key properties: specific gravity 5.65; Yellow to ocher-yellow streak; optically biaxial.
IMA symbol Dmt, grandfathered status — known before the IMA’s founding, named in 1924.
Found in pockets of torbernite in the oxidized zone of a uranium deposit (Shinkolobwe, Congo).
It is found associated with Torbernite (Shinkolobwe, Congo); uranophane, kasolite, autunite (near Nogales, Arizona, USA); kasolite (Goodsprings, Nevada, USA).
The mineral was named to honor André Hubert Dumont (1809–1857), Belgian geologist.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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