Colorless very shiny crystals of the rare phosphate mineral nefedovite from the type locality in Khibiny (Khibiny Massif, Murmansk Oblast, Russian Federation). Very nice under the microscope. Ex Vandenbroucke Museum collection specimen, from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Nefedovite
Nefedovite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Na₅Ca₄(PO₄)₄F.
It crystallizes in the tetragonal crystal system (space group I-4).
Key properties: Mohs hardness 4.5; specific gravity 3.01; Vitreous luster; optically biaxial.
IMA symbol Nef, IMA status: approved, named in 1982.
Found in pegmatitic segregations in nepheline syenite in a differentiated alkalic massif.
It is found associated with Apatite, nacaphite, eudialyte, delhayelite, canasite, djerfisherite, rasvumite, orthoclase, alkalic amphibole, titanite.
The mineral was named to honor Dr. Yevgeny I. Nefedov (1910–1976), Russian mineralogist, St. Petersburg, Russia, involved in the discovery of a number of Kola minerals.