Pyrochlore is a group of minerals Formula: (Na,Ca)2Nb2(O,OH,F)2
Specific gravity: 4.5
Hardness: 5 to 5½
Streak: light brown, yellowish brown
Colour: orange, brownish red, brown, black
Solubility: Insoluble in water, soluble with decomposition in sulphuric acid
Common impurities: U,Th
Plutonic igneous environments
Pyrochlore is a primary mineral, forming in pegmatites and in igneous rocks
dominated by carbonate minerals.
It is an accessory mineral
in silica-poor rocks, often occurring with magnetite,
apatite and zircon.
It also accumulates in some detrital deposits.
At the Silver Crater mine, Hastings county, Ontario, Canada, pyrochlore occurs in a small carbonatite together with zircon crystals (R&M 94.5.414).
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