Polycrase

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
Identification
Mohs scale hardness	5-6
Specific gravity	5
Other characteristics	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)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 Rasvåg on the island of Hidra, south of the town of Flekkefjord, Norway. It is found in Sweden, Norway, and the United States.

External links

• Mindat with location data
• Webmineral