Jahnsite-(CaMnZn)
Jahnsite-(CaMnZn) is an IMA-recognized mineral species in the phosphate class, with the chemical formula CaMn²⁺Zn₂Fe³⁺₂(PO₄)₄(OH)₂·8H₂O.
It crystallizes in the monoclinic crystal system (space group P2/a). It is a member of the Jahnsite structural group.
Key properties: specific gravity 2.87; optically biaxial.
IMA symbol Jah-CaMnZn, IMA status: approved, named in 2019.
Found in an oxidized nodule of former triphylite, now replaced by phosphophyllite. A low temperature, secondary mineral produced through alteration of primary phosphates in zoned granitic pegmatite.
It is found associated with Chalcophanite, hopeite, jahnsite-(CaMnMn), Zn-bearing laueite, scholzite/ parascholzite, parahopeite, schmidite, stewartite, vivianite.
Root name, Jahnsite, indicates a member of the group with M(3) = Fe3+; the suffix indicates sequentially the dominant atom in the X, M(1), and M(2) structural positions.