Polycrase

Polycrase
Polycrase crystal from Rio Pomba, Minas Gerais, Brazil
General
Category	Mineral
Formula (repeating unit)	(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

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 Rasvag, , near Flekkefjord, Norway. It is found in Sweden, Norway, and the United States.

References[]

• Mindat with location data
• Webmineral