Autunite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NameAutunite
Chemical FormulaCa(UO₂)₂(PO₄)₂·10-12H₂O
Mohs Hardness2.5
Crystal Systemtetragonal
Lustervitreous
Streak Colorpale yellow
Cleavageperfect on {001}
Fractureuneven
Specific Gravity3.1
Colorsyellow-green, bright green
Transparencytransparent
Type LocalityLes Oudots Quarry, Issy-l'Evêque, Saône-et-Loire, Burgundy, France
Mineral GroupPhosphates
Usesuranium ore, collector, scientific research
Associated Mineralsquartz, feldspar, uraninite, torbernite
Rarityuncommon
Description
This specimen displays bright yellow-green, granular to platy aggregates of autunite covering a light-colored rock matrix. Under ultraviolet light, the mineral exhibits a strong, vivid green fluorescence.
Geological Context
Autunite is a secondary uranium mineral that forms in the oxidized zones of uranium ore deposits, typically as an alteration product of primary uranium minerals like uraninite. It is often found in granite pegmatites and other igneous or metamorphic rocks.
