Fersmanite Dimensions: 2.7 cm x 2.6 cm x 1.8 cm Locality: Vein No. 1 of Labuntsov, Astrophyllite Stream, Eveslogchorr Mt, Khibiny Massif, Murmansk Oblast, Russia A better than average specimen of the very rare sorosilicate, fersmanite, which was named after Aleksandr Evgenievich Fersman, the founder of the Fersman Mineralogical Museum in Moscow, Russia. The best examples are those from the Kola Peninsula and good specimens are rarely available. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Fersmanite
Fersmanite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₄(Na,Ca)₄(Ti,Nb)₄(Si₂O₇)₂O₈F₃.
It crystallizes in the monoclinic crystal system (space group C2/c).
Key properties: Mohs hardness 5–5.5; specific gravity 3.44–3.46; White with pale brownish tint streak; Vitreous luster; optically biaxial.
IMA symbol Fsn, grandfathered status — known before the IMA’s founding, named in 1929.
Found in aegirine-rich nepheline pegmatites in a differentiated alkalic massif (Khibiny massif, Russia).
It is found associated with Feldspar, pectolite, apatite, aegirine, lamprophyllite, rinkite, sulfides.
The name refers to Academician Aleksandr Evgen'evich Fersman (1883-1945), eminent Russian mineralogist, geochemist, and gemologist.