Light yellow single crystal of vuonnemite from one of the few known localities worlwide. From: Shkatulka Pegmatite, Lovozero Massif, Kola, Russian Federation. — Photo: David Hospital · CC BY-SA 4.0
Vuonnemite
Vuonnemite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₆Na₂Nb₂Na₃Ti(Si₂O₇)₂(PO₄)₂O₂(OF).
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Seidozerite-Lamprophyllite structural group.
Key properties: Mohs hardness 2–3; specific gravity 3.13–3.15; White streak; Vitreous to greasy luster; optically biaxial.
IMA symbol Vn, IMA status: approved, named in 1973.
Found in albitized alkalic rocks in differentiated alkalic massifs (Kola Peninsula, Russia); in a transition zone between two nepheline syenites (Il¶³maussaq intrusion, Greenland).
It is found associated with Albite, microcline, nepheline, aegirine, lorenzenite, cancrinite, s¶erandite, villiaumite (Kola Peninsula, Russia); microcline, natrolite, epistolite.
The name refers to the occurrence near the Vuonnemiok River, Khibiny massif, Kola Peninsula, Russia.