
Dark brown to green lustrous grain of euxenite-(Y) in potassium feldspar. From Keller Lake road occurrence, Waupaca County, Wisconsin. Field of view is 7.0 mm left to right. (Dan Behnke specimen and image.)

Euxenite-(Y) from the Nine Mile pluton near Wausau in Marathon County, Wisconsin. Scanning electron microscope image. (Photo by Al Falster.)
Formula: (Y, Ca, Ce,U, Th)(Nb,Ta,Ti)2O6 Orthorhombic
Description: Euxenite is an uncommon mineral found in complex granitic pegmatites.
MARATHON COUNTY: Euxenite-(Y) occurs “abundantly” as crystal clusters and masses several centimeters long in a pegmatite at the the Red Rock Granite North Pit along Spring Brook Road, near the interestion with Highway 107, south of Marathon City. A euxenite-like phase has also been identified at the Ladick Quarry (sec. 19 and 20 T. 27N. R.6E.). (Buchholz and Simons, 2002). A euxenite mineral may also have been found at the Koss Pit on County Trunk O.
WAUPACA COUNTY: Euxenite-(Y) occurs as small yellow-brown crystals from road cuts in pegmatite cutting granite along County G near Keller Lake, NE of Big Falls. Associated minerals include fluorite, K feldspar, bastnaesite group minerals, allanite and various sulfides. (Tom Buchholz, 2002, personal communication)