Formula: Na2Ca(UO2)(CO3)3.5-6H2O
Hydrated normal carbonate, uranyl mineral
Crystal System: Trigonal
Specific gravity: 2.8 measured, 2.86 calculated
Hardness: 2½
Colour: Bright green to yellow-green
Luminescence: Fluorescent bright pastel green under short wave and long wave UV
Solubility: Soluble in water

Sedimentary environments
Hydrothermal environments

Andersonite is an uncommon secondary mineral, formed in the oxidised zone of uranium-bearing hydrothermal polymetallic deposits; it may be post-mine, coating walls of mine tunnels. Associated minerals include schröckingerite, bayleyite, swartzite, boltwoodite, liebigite and gypsum (HOM).


At the type locality, the Hillside mine, Bozarth Mesa, Bagdad, Eureka Mining District, Yavapai County, Arizona, USA, andersonite occurs as a post-mining efflorescences on mine walls, associated with swartzite, schröckingerite, gypsum and bayleyite (Mindat, Dana).

Andersonite from the Hillside Mine - Image

At Mount Pisgah, Jim Thorpe, Carbon county, Pennsylvania, USA, andersonite is associated with liebigite and carnotite (Dana).

At the Atomic King no. 2 Mine, Lower Kane Creek Mining District, San Juan county, Utah, USA, thick crusts of andersonite were mined as ore, and crystals up to 1 cm in size were found (Lauf2).

Andersonite from the Atomic King no. 2 Mine - Image

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