Niocalite

niocalite

diopside

pyrochlote

perovskite

Formula: Ca₇Nb(Si₂O₇)₂O₃F
Sorosilicate (Si₂O₇ groups), wöhlerite group
Crystal System: Monoclinic
Specific gravity: 3.32 measured, 3.29 calculated
Hardness: 6
Streak: White
Colour: Lemon-yellow, colourless in transmitted light
Common impurities: Ti,Zr,Al,Y,Fe,Ta,Mn,MgNa,K,P,H₂O
Environments

Carbonatites

Localities

At the type locality, the Bond zone, Oka complex, Oka, Deux-Montagnes RCM, Laurentides, Quebec, Canada, niocalite occurs in a coarse-grained strontian carbonatite. Associated minerals include calcite, magnetite, apatite, diopside, biotite, pyrochlore and perovskite variety dysanalyte (AM 41.785-786, HOM, Dana).

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