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Formula: Y(Ti,Nb)2(O,OH)6
Multiple oxide, euxenite group
Specific gravity: 4.9 to 5.1
Hardness: 5 to 6
Streak: Yellowish, greyish, reddish brown
Colour: Black
Common impurities: Ca,Ce,U,Th,Ta
RADIOACTIVE
Environments
Polycrase-(Y) is found in K-rich granite pegmatites, and rarely as a
detrital mineral. Associated minerals include monazite,
beryl, columbite,
magnetite, fluorite,
biotite, ilmenite,
xenotime, gadolinite,
allanite, zircon and
garnet
(Dana, HOM ). It is usually metamict, and only very rarely, crystalline samples with incipient metamictisation have
been reported
(Mindat).
Localities
Well crystallised polycrase-(Y) is found in numerous localities in the Ankazobe District, Analamanga, Madagascar,
in K-rich pegmatites with beryl, columbite,
monazite and pyrochlore group
minerals
(Dana).
The type locality is the Rasvåg feldspar quarries, Hidra, Flekkefjord, Agder, Norway.
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