Metatorbernite Locality: Margabal Mine, Entraygues-sur-Truyère , Aveyron , Midi-Pyrénées , France) Size: 4 x 3x 1.8 cm. — Photo: Didier Descouens · CC BY-SA 4.0
Metatorbernite
The dehydrated pseudomorph of torbernite — a green platy radioactive copper-uranium phosphate.
Intro adapted from Wikipedia (CC BY-SA).
Metatorbernite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Cu(UO₂)₂(PO₄)₂·8H₂O.
It crystallizes in the tetragonal crystal system (space group P4/nmm).
Key properties: Mohs hardness 2.5; specific gravity 3.52–3.7; Vitreous, subadamantine, pearly on {001} luster; refractive index 1.625; optically uniaxial.
IMA symbol Mtor, grandfathered status — known before the IMA’s founding, named in 1916.
Typically a secondary mineral, a dehydration product of torbernite developed during weathering; formed directly above 75 flC.
It is found associated with Torbernite, meta-autunite.
The prefix meta- denotes the dehydration product of torbernite.