Polycrase

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)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.

CategoryMinerals

Formula(Y,Ca,Ce,U,Th)(Ti,Nb,Ta)₂O₆

IMA symbolPlc^[1]

Mohs scale hardness5-6

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Polycrase
Polycrase crystal from Rio Pomba, Minas Gerais, Brazil
General
Category	Minerals
Formula	(Y,Ca,Ce,U,Th)(Ti,Nb,Ta)2O6
IMA symbol	Plc[1]
Identification
Mohs scale hardness	5-6
Specific gravity	5
Other characteristics	Radioactive

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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.