Formula: YNbO4. Tetragonal
Description: Fergusonite-(Y) is a rare earth mineral found in granitic and other pegmatites. It may also be found in placer deposits from the weathering and erosion of such bodies.
MARATHON COUNTY: Tiny acicular crystals of fergusonite-(Y), approximately 100 microns long, are found in pegmatites cutting amphibole syenite in the Stettin area. These can be found growing on cheralite. (Falster et al., 2000).