Chemistry:Polycrase

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Polycrase
Polycrase-(Y)-619586.jpg
Polycrase crystal from Rio Pomba, Minas Gerais, Brazil
General
CategoryMineral
Formula
(repeating unit)
(Y,Ca,Ce,U,Th)(Ti,Nb,Ta)
2
O
6
Identification
Mohs scale hardness5-6
Specific gravity5
Other characteristicsRadioactive.svg Radioactive

Polycrase or polycrase-(Y) is a black or brown metallic complex uranium yttrium oxide mineral with the chemical formula (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)
2
O
6
. 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

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode2021MinM...85..291W.