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Formula: (H2O,☐)2Nb2(O,OH)6(H2O)
Multiple oxide, pyrochlore group,
niobium-bearing mineral
Crystal System: Isometric
Specific gravity: 3.4 to 3.48 measured
Hardness: 4 to 4½
Streak: White
Colour: Greenish, greenish white
Common impurities: Sr,Ca,Ti,K
Environments
Carbonatites
Hydrothermal environments
The mineral was approved as "kalipyrochlore" in 1977 and redefined as hydropyrochlore in 2010.
Localities
At the type locality, the Lueshe Mine, Bwito, Rutshuru Territory, North Kivu, DR Congo, hydropyrochlore was
found in the alluvial deposits, and is common in the residual soils of the
carbonatite deposit. The
niobium mineralisation is characterized by sodium-calcium
pyrochlores in the unweathered søvites (coarse-grained
calcite-carbonatites),
by lueshite associated with
vermiculite in fenites, and
by columbite often associated with
fersmite; both columbite and
fersmite occur as pseudomorphs
after pyrochlore.
Hydropyrochlore occurs as greenish octahedra, some of which are corroded, usually 3 to 5mm in size, but
sometimes up to 10mm. The main inclusions are ilmenite,
rutile and barium-bearing
goyazite. The partially weathered
pyrochlore was shown to consist of an internal zone of
sodium-cacium pyrochlore and an external zone of hydropyrochlore.
Hydropychlore is formed from pyrochlore by leaching of sodium,
calcium, and fluorine in waters rich in potassium ions
(AM 63: 528-530 as kalipyrochlore)
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