Formula: (Na,Pb,Ca,REE,U)2Nb2O6F
Oxide, pyrochlore group, uranium- and niobium- bearing mineral
Crystal System: Isometric
Specific gravity: 5.275 calculated
Hardness: 4 to 4½
Streak: Light yellow
Colour: Brownish yellow to reddish orange
Luminescence: Non-fluorescent under UV

Plutonic igneous environments


At the type locality, the Boziguoer intrusion, Baicheng county, Aksu Prefecture, Xinjiang, China, fluornatropyrochlore was found in the alkaline intrusive granitic rocks. The igneous intrusion played an important role in niobium-tantalum mineralisation and contributed to the high content of rubidium, uranium, thorium, zirconium and rare earth elements. The Boziguoer rock is a niobium-, tantalum- and rare-earth-element-rich plutonic rock.
There are different mineral parageneses in the eastern and western mine areas. As accessory minerals, xenotime-(Y), chevkinite-(Ce) and fergusonite-(Y) are mainly found in aegirine granite in the western mining area, and thorite and columbite-(Fe) are mainly found in a monzogranite in the eastern mining area. However, fluornatropyrochlore, together with astrophyllite, zircon, fluorite, fluocerite-(Ce) and monazite, are commonly found in both of the mining areas. Other common minerals are microcline, albite, anorthite, quartz, aegirine, a sodic amphibole, biotite, rutile, fluorite and members of the columbite-(Fe)-columbite-(Mn) series. Fluornatropyrochlore mainly occurs in a niobium-tantalum-rich alkali syenite deposit (CM 53.455-460).

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