Polycrase-(Y)

polycrase

gadolinite

xenotime

monazite-(Ce)

Images

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

Pegmatites

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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