Red brown crystals of Ronneburgite with yellow white Picromerite (Picture size: 2 mm) Locality: Open pit Lichtenberg, Ronneburg, Thuringia, Germany — Photo: Thomas Witzke · CC BY-SA 3.0 de
Ronneburgite
Ronneburgite is an IMA-recognized mineral species in the vanadate class, with the chemical formula K₂MnV₄O₁₂.
It crystallizes in the monoclinic crystal system (space group P2_1/n).
Key properties: Mohs hardness 3; specific gravity 2.84; Orange brownish streak; Adamantine luster; optically biaxial.
IMA symbol Rbu, IMA status: approved, named in 1998.
Found as a secondary mineral in a metamorphosed black shale uranium deposit.
It is found associated with Hummerite, gypsum, epsomite, picromerite, hematite, an unidentified K-Mg-Mn- vanadate.
The name refers to the Ronneburg uranium deposit, Germany.