Pyrochlore

Formula: (Na,Ca)₂Nb₂O₆(OH,F)

Mohs scale hardness: 5-5,5

Specific gravity: 4,5-4,9 g/cm³

^Ta₂^O₅ max ^{content: 7 %}

^Nb₂^O₅ ^{content: 40-80 %}

^{Rare earth elements: Ce}

^{Rare earth content: REOmax=11,5 %}

^{Other constituents: Ti, Th, U}

^{Mineralklasse: Oxide, Hydroxide}

^{Application: Raw material for production of Niobium and Tantalum}

The mineral is associated with the metasomatic end stages of magmatic intrusions. Pyrochlore crystals are usually well formed (euhedral), occurring usually as octahedra of a yellowish or brownish color and resinous luster. It is commonly metamict due to radiation damage from included radioactive elements.

Pyrochlore occurs in pegmatites associated with nepheline syenites and other alkalic rocks. It is also found in granite pegmatites and greisens. It is characteristically found in carbonatites. Associated minerals include zircon, aegirine, apatite, perovskite and columbite.

The three largest producers of niobium ore are mining pyrochlore deposits. The largest deposit in Brazil is the CBMM mine located south of Araxá, Minas Gerais, followed by the deposit of the Catalão mine east of Catalão, Goiás. The third largest deposit of niobium ore is Niobec mine west of Saint-Honoré near Chicoutimi, Quebec.

Pyrochlore ore typically contains greater than 0.05% of naturally occurring radioactive uranium and thorium.

References

1. https://en.wikipedia.org

2. https://en.wikipedia.org/wiki/Pyrochlore

3. http://www.dakotamatrix.com/products/6578/pyrochlore

4. http://mrdata.usgs.gov/ree/ree.php?mineral=pyrochlore