Fluorcalciopyrochlore

fluorcalciopyrochlore

britholite-(Ce)

bastnasite-(Ce)

riebeckite

Images

Formula: (Ca,Na)2(Nb,Ti)2O6F
Oxide, pyrochlore group, pyrochlore supergroup, niobium- and titanium- bearing mineral
Crystal system: Isometric
Specific gravity: 4.34 calculated
Hardness: 5
Streak: Light yellow
Colour: Brownish yellow to reddish orange
Solubility: Insoluble in hydrochloric or nitric acid
Environments

Carbonatites

Fluorcalciopyrochlore is a relatively new mineral, approved in 2013.

Localities

The type locality is the Bayan Obo deposit, Bayan Obo, Bayan Obo mining district, Baotou City, Inner Mongolia, China. The deposit is the world’s largest known rare earth element ore deposit and a major iron and niobium producer as well. Fluorcalciopyrochlore occurs in carbonatites, disseminated as fine grains and veinlets or scattered between dolomite crystals. The mineral is often euhedral or subhedral, associated with dolomite and calcite, with all three minerals crystallising at the same time. Other associated minerals are aegirine, riebeckite, diopside, fluorite, baryte, phlogopite, britholite-(Ce), bastnäsite-(Ce), zircon, magnetite, pyrite, fersmite, columbite-(Fe), monazite-(Ce) and rutile.
While most often fluorcalciopyrochlore occurs as subhedral or allotriomorphic grains, it sometimes forms as octahedra, dodecahedra and cubes, or combinations thereof. Crystals generally range in size from 0.01 to 0.3 mm. It is brownish yellow to reddish orange in colour with a light yellow streak, translucent to transparent with an adamantine to greasy lustre on fractured surfaces and a conchoidal fracture (CM 54.5.1285-1291).

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