Polycrase (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)2O6 Orthorhombic

Description: Polycrase is a rare black metallic mineral found as flattened prismatic crystals or masses in chemically complex pegmatites.

MARATHON COUNTY: Small grains of polycrase (Y) occur in pegmatite at the Koss Pit several miles east of Wausau, WI. (Tom Buchholz, 2002, pers. com.)

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