Bergenite Locality: Shaft 362, Mechelgrün, Plauen, Vogtland, Saxony, Germany Beautiful Bergenite crystals from Shaft 362, Mechelgrün, Saxony, Germany. Field of view 7 mm. Photo and specimen Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0
Bergenite
A rare uranyl phosphate of the phosphuranylite group, built on a distinctive sheet geometry.
Intro adapted from Wikipedia (CC BY-SA).
Bergenite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Ca₂Ba₄(UO₂)₉O₆(PO₄)₆·16H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Phosphuranylite structural group.
Key properties: Mohs hardness 2.5; specific gravity 4.1; Pale yellow streak; refractive index 1.698; optically biaxial.
IMA symbol Bgn, grandfathered status — known before the IMA’s founding, named in 1959.
On a mine dump (Streuberg, Germany) and in uranium deposits (Black Forest, Germany). In graphitic uranium ore (Korea).
It is found associated with “Uranocircite”, torbernite, autunite, dewindtite, barian uranophane (Streuberg, Germany).
The name refers to the first-noted occurrence of the mineral near Bergen, Germany.