Rameauite is a hydrated complex uranyl oxide mineral with formula K₂Ca(UO₂)₆OH₁₆·H₂O or K₂CaU⁶⁺₆O₂₀·9H₂O.Handbook of Mineralogy
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Crystallography

Rameauite has four observed forms which are , , and . The angles between these faces are ^ = 58°40' and ^ = 49° 50'. The crystals are always twinned on and they are flattened parallel to , and elongated parallel to . The mineral rameauite is an example of a

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

mineral and appears pseudo-hexagonal. I has unit cell dimensions of: a= 13.97, b= 14.26, c= 14.22 with β = 121.02°.Cesbron, F., W.L. Brown, P. Bariand, and J. Geffroy (1972) Rameauite and agrinierite, two new hydrated complex uranyl oxides from Margnac, France. Mineralogical Magazine, 38, 781–789.
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Occurrence

It was first described in 1972 for an occurrence in the Margnac Mine, Compreignac, Haute-Vienne,

Limousin Limousin (; oc, Lemosin ) is a former administrative region of southwest-central France. On 1 January 2016, it became part of the new administrative region of Nouvelle-Aquitaine. It comprised three departments: Corrèze, Creuse, and Haute-Vienn ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

and named after Jacques Rameau (1926–1960), French prospector at the "Commissariat à l'Energie Atomique", who discovered the deposit where the mineral occurs. Mindat.org
/ref> In addition to the type locality in France it has been reported from the Orphan Mine on the south rim of the Grand Canyon in

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

and on Rhyolite Ridge,

Esmeralda County, Nevada Esmeralda County is a county in the southwestern portion of the U.S. state of Nevada. As of the 2020 census, the population was 729, making it the least populous county in Nevada. Esmeralda County does not have any incorporated communities. It ...

References

{{Reflist Oxide minerals Uranium(VI) minerals Monoclinic minerals Minerals in space group 15 Potassium minerals