White crystals of the rare phosphate mineral natrophosphate associated to orange villiaumite from the type locality in Rasvumchorr (Rasvumtchorr, Khibiny, Kola, Russian Federation). — Photo: David Hospital · CC BY-SA 4.0
Natrophosphate
Natrophosphate is an IMA-recognized mineral species in the phosphate class, with the chemical formula Na₇(PO₄)₂F·19H₂O.
It crystallizes in the cubic crystal system (space group Fd3c).
Key properties: Mohs hardness 1–2.5; specific gravity 1.71–1.72; Vitreous to greasy, waxy to frosty on exposure luster.
IMA symbol Nap, IMA status: approved, named in 1971.
A rare mineral found in ijolite-urtite pegmatite in a differentiated alkaline massif (Kola Peninsula, Russia); in sodalite xenoliths in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada).
It is found associated with Villiaumite, aegirine, delhayelite, strontian apatite, natrolite, pectolite, albite (Mt. Yukspor, Kola Peninsula, Russia); villiaumite, nahpoite, dorfmanite.
The name refers to sodium, natrium, and phosphate in the composition.