Polycrase

Polycrase or polycrase-(Y) is a black or brown metallic complex uranium yttrium oxide mineral with formula: (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)₂O₆. It is amorphous. It has a Mohs hardness of 5 to 6 and a specific gravity of 5. It is radioactive due to its uranium content (around 6%). It occurs in granitic pegmatites.

Polycrase forms a continuous series with the niobium rich rare earth oxide euxenite.

It was first described in 1870 at Rasvag, Hidra (Hittero) Island, near Flekkefjord, Norway. It is found in Sweden, Norway, and the United States.

References

Simple	Anatase Brookite Geikielite Rutile

Mixed	Aeschynite-(Y) Armalcolite Betafite Euxenite Freudenbergite Haggertyite Ilmenite Keilhauite Latrappite Perovskite Polycrase Zimbabweite Zirconolite Zirkelite

Other

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