Jahnsite-(CaMnFe) Locality: Hagendorf South Pegmatite (Cornelia Mine; Hagendorf South Open Cut), Hagendorf , Waidhaus , Vohenstrauß , Oberpfälzer Wald , Upper Palatinate , Bavaria , Germany ( Locality at mindat.org ) Yellow Jahnsite-(CaMnFe) (analysed by EPMA and Moessbauer spectroscopy) on Rockbridgeite. Picture width 1 mm. Collection and Photo Christian Rewitzer — Photo: Christian Rewitzer · CC BY-SA 3.0
Jahnsite-(CaMnFe)
Jahnsite-(CaMnFe) is an IMA-recognized mineral species in the phosphate class, with the chemical formula CaMn²⁺Fe²⁺₂Fe³⁺₂(PO₄)₄(OH)₂·8H₂O.
It crystallizes in the monoclinic crystal system. It is a member of the Jahnsite structural group.
Key properties: Mohs hardness 4; specific gravity 2.86; [Vitreous to subadamantine.] luster; optically biaxial.
IMA symbol Jah-CaMnFe, IMA status: approved, named in 1978.
A late-stage hydrothermal decomposition product of primary phosphate minerals in complex granite pegmatites.
It is found associated with Rockbridgeite (Fletcher mine, New Hampshire, USA); frondelite, bermanite, huréaulite, strunzite, johnsomervilleite (Sapucaia mine, Brazil).
By analogy to jahnsite-(CaMnMg); the suffix indicates sequentially the dominant atom in the X, M(1), and M(2) structural positions.