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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 crystallizes in the orthorhombic system with typically radial prismatic crystal form. 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.

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


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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Polycrase". A list of authors is available in Wikipedia.
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