Agrinierite - Encyclopedia

    Class : Oxides and hydroxides
    Subclass : Uranyl hydroxides
    Crystal System : Monoclinic
    Chemistry : (K2,Ca,Sr)U3O10 4H2O
    Rarity : Very rare

Agrinierite is a hydrated oxide of uranium discovered during the exploitation of the uranium deposit of Margnac (Haute-Vienne, France), the only site in the world where it is known until today. It owes its name to Henri Agrinier, engineer at the Mineralogy Laboratory of the Atomic Commission of France. It appears at the periphery of uraninite nodules accompanied by other uranium oxides which result like it from the transformation of uraninite (becquerelite, schoepite, compreignacite, rameauite, etc...). Agrinierite occurs as small tabular orange crystals, transparent to translucent, submillimeter in size, frequently twinned which gives them a pseudohexagonal appearance. 

Main photo : Agrinierite from Margnac, Haute-Vienne, France © Michel Bretheau

Agrinierite in the World

This mineral is only described in France.

Agrinierite in France

This extremely rare mineral is only described at the Margnac Mine in Compreignac (Haute-Vienne), the type locality.


This mineral twins with {110} as plane of composition.

Fakes and treatments

No fake reported for this mineral species.

Hardness : Undefined
Density : 5.7
Fracture : Irregular to conchoidal
Trace : Yellow

TP : Translucent to transparent
RI : Unmeasured
Birefringence : Unmeasured
Optical character : Uniaxial +
Pleochroism : None
Fluorescence : None

Solubility : None

Magnetism : None
Radioactivity : Very high


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