Andersonite - Encyclopedia

    Class : Carbonates, Nitrates, Borates
    Subclass : Uranyl carbonates
    Crystal System : Trigonal
    Chemistry : Na2Ca(UO2)(CO3)3 6H2O
    Rarity : Rare

Andersonite is a green-yellow secondary uranium carbonate which crystallizes in the oxidation zone of uranium deposits, associated with other secondary minerals of this metal (liebigite, carnotite, etc...). It was named in honor of Charles Alfred Anderson, a member of the U.S. Geological Survey, who discovered it. It is a mineral which forms small rhombohedral crystals of 1 cm at most, sometimes pseudocubic, as well as thick encrustations. This mineral has no particular use.

Andersonite from Atomic King Mine, Utah, USA
© Rock Currier
Andersonite from Ambrosia Lake, New-Mexico, USA
© Brian Kosnar
Fluorescent andersonite from Markey Mine, Utah, USA
© Travis Olds
Andersonite from Mas Lavayre, Lodève, Hérault, France
© F. Bonnet

Andersonite in the World

Andersonite is particularly known for its green-yellow efflorescences which it forms in the galleries of uranium mines (Hillside, Arizona and Geevor in England). The best samples, however, come from the uranium deposits that dot the Colorado Plateau : the mines in the district of Moab (Utah), where magnificent 10 mm crystals have been collected, and Ambrosia Lake, near Grants in New Mexico.

Main photo : Andersonite from Bukov Mine, Czech Republic - © Serge Lavarde and Luigi Chiappino's collection

Andersonite in France

In France, andersonite is reported in sub-millimetric crystals in the Mas Lavayre quarry south of Lodeve (Hérault).


No twin report for this mineral species.

Fakes and treatments

No fake reported for this species.

Hardness : 2.5
Density : 2,80
Fracture : Irregular
Trace : Yellow

TP : Translucent to transparent
RI : 1.520 to 1.540
Birefringence : 0.020
Optical character : Uniaxial +
Pleochroism : Not visible
Fluorescence : Green-yellow

Solubility : Water

Magnetism : None
Radioactivity : Strong