Hallimondite
Hallimondite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Pb₂(UO₂)(AsO₄)₂·nH₂O.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 2.5–3; specific gravity 6.39; Pale yellow streak; Subadamantine luster; optically biaxial.
IMA symbol Hll, IMA status: approved, named in 1965.
A secondary mineral found on a museum specimen from an oxidizing As-Pb-bearing deposit, produced through alteration of galena.
It is found associated with Hiigelite, mimetite, barite, galena, quartz.
The mineral was named to honor Dr. Arthur Francis Hallimond (1890-1968), British mineralogist, London, England, for his work with secondary uranium minerals.
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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