Jahnsite-(NaFeMg)
Jahnsite-(NaFeMg) is an IMA-recognized mineral species in the phosphate class, with the chemical formula NaFe³⁺Mg₂Fe³⁺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: Mohs hardness 4; specific gravity 2.58; White streak; Vitreous luster; optically biaxial.
IMA symbol Jah-NaFeMg, IMA status: approved, named in 2007.
A late-stage hydrothermal decomposition product of triphylite in a complex granitic pegmatite.
It is found associated with Heterosite, leucophosphite, dufrénite, barbosalite, rockbridgeite, mitridatite, ushkovite.
Root name, Jahnsite, indicates a member of the group with M3 = Fe3+; suffixes indicate cations in X, M1, and M2.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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