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Oxides & Hydroxide

Compreignacite

K₂(UO₂)₆O₄(OH)₆·7H₂O
Crystal systemOrthorhombic
ClassOxides & Hydroxide
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Compreignacite specimen

Compreignacite from the type locality, Mine de Margnac, Compreignac, Département Haute-Vienne, Region Limousin, Frankreich. (Field of view: 4.6 mm) — Photo: BLFrank · CC BY-SA 4.0

Compreignacite

Compreignacite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula K₂(UO₂)₆O₄(OH)₆·7H₂O.

It crystallizes in the orthorhombic crystal system (space group Pnnm). It is a member of the Compreignacite structural group.

Key properties: specific gravity 5.03; Pale yellow streak; optically biaxial.

IMA symbol Cgn, IMA status: approved, named in 1964.

Found as a very rare oxidation product of “pitchblende” in uranium deposits.

It is found associated with Uraninite, cuprosklodowskite, uranophane, zeunerite, schoepite, brochantite, connellite, cerian agardite (Margnac mine, France); cuprosklodowskite, uranophane.

The name refers to Compreignac, the village near the Margnac mine, France.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet. Browse more C minerals or help write this entry.