Niobophyllite

niobophyllite

arfvedsonite

neptunite

eudidymite

Images

Formula: K₂NaFe²⁺₇(Nb,Ti)₂(Si₄O₁₂)₂O₂(OH)₄(O,F)
Inosilicate (chain silicate), astrophyllite group, niobium-bearing mineral
Crystal System: Triclinic
Specific gravity: 3.42 measured, 3.406 calculated
Hardness: 3 to 4
Colour: Brown
Common impurities: Al,Ta,Mg,Ca,H₂O
Environments

metamorphic environments

Localities

At the type locality, Mann 2, Seal Lake alkaline complex, Labrador, Newfoundland and Labrador, Canada, niobophyllite occurs as discontinuous seams and polycrystalline aggregates within a paragneiss, consisting chiefly of albite and arfvedsonite, intruded by an alkaline syenite. Associated minerals include albite, arfvedsonite, aegirine-augite, barylite, eudidymite, neptunite, manganese-bearing pectolite, pyrochlore, joaquinite, sphalerite and galena (CM 8.40-52, HOM).

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