Outstanding orange crystals of the new and extremely rare phosphate mineral kummerite (IMA 2015-036), associated to dark green beraunite needles. SEM/EDS and DRX analyzed. Only one known locality worldwide! From: Hagendorf, Oberpfalz, Bavaria, Germany. — Photo: David Hospital · CC BY-SA 4.0
Kummerite
Kummerite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Mn²⁺Fe³⁺Al(PO₄)₂(OH)₂·8H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Laueite structural group.
Key properties: specific gravity 2.34; White streak; Vitreous luster; optically biaxial.
IMA symbol Kum, IMA status: approved, named in 2015.
Found as a secondary mineral in pegmatite formed by the reaction of laueite with Al-bearing hydrothermal fluids.
It is found associated with Zwieselite, Zn- and Al-bearing beraunite, Al-bearing frondelite, jahnsite-(CaMnMn).
The mineral was named to honor Rudolf Kummer (1924-1982).