Class : Oxides and hydroxides
    Subclass : Uranyl hydroxides
    Crystal system : Monoclinic
    Chemistry : K₂CaU₆O₂₀ 9H₂O
    Rarity : Very rare

Rameauite is an extremely rare hydrated oxide of uranium discovered during the exploitation of the Margnac uranium deposit (Haute-Vienne, France). It was observed in alteration zones at the periphery of uraninite nodules (pitchblende facies) and results from the first stages of transformation of this mineral. It was named in honor of Jacques Rameau, Prospector at the French Atomic Energy Commission (C.E.A.) who discovered the deposit where the mineral was found. Rameauite occurs in small tabular orange crystals reaching 1 mm, constantly twinned which gives them pseudohexagonal shapes. These crystals are flattened along {010} and elongated parallel to [001]. Rameauite appears in the company of other uranium oxides (becquerelite, schoepite, compreignacite, agrinierite, etc...), calcite, uranophane and of course uraninite.

Main photo : Rameauite from Margnac Mine, Compreignac, Haute-Vienne, France © Chuck Adan

Systematically twinned on {100}.

No fakes listed for this mineral species.