Fersmanite

fersmanite

lamprophyllite

pectolite

rinkite-(Ce)

Images

Formula: Ca₄(Na,Ca)₄(Ti,Nb)₄(Si₂O₇)₂O₈F₃
Sorosilicate (Si₂O₇ groups), titanium- and niobium- bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.44 to 3.46 measured, 3.159 calculated
Hardness: 5 to 5½
Streak: White with pale brownish tint
Colour: Dark brown to golden yellow
Solubility: Soluble in acids
Environments

Pegmatites
Hydrothermal environments

Fersmanite occurs in aegirine-rich pegmatite veins in nepheline syenite; it is hydrothermal in origin; sometimes it alters to lamprophyllite (Dana). Associated minerals include feldspar, pectolite, apatite, aegirine, lamprophyllite, rinkite and sulphides (HOM).

Localities

At the type locality, Vein No. 1 of Labuntsov, Astrophyllite Stream, Eveslogchorr Mt, Khibiny Massif, Murmansk Oblast, Russia, fersmanite is found in aegirine-nepheline feldspar veins that cut the nepheline syenite. Associated minerals include feldspar, aegirine, lamprophyllite, apatite, pectolite and rinkite-(Ce) (AM 16.92, Mindat).

Fersmanite from Vein No. 1 - Image

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