GADOLINITE Be3FeY2Si2O10 Monoclinic

Description: Gadolinite is an extremely rare mineral found in certain complex granitic pegmatites.

Gadolinite (Y), WI

Black gadolinite-(Y) mass (about 4 mm across) in granite. Keller Lake, Waupaca County, WI. W. Cordua photo.

Gadolinite (Y), WI

Gadolinite-(Y) in pegmatite, near Keller Lake, Waupaca County, WI. Largest crystal (black) about 0.5 cm. across.

SHAWANO COUNTY: Black to dark green anhedral masses of gadolinite up to several cm. in diameter are found in the complex pegmatite exposed near the Embarass River, south of the Tigerton Dells in the NE SW NE Sec. 15 T.26N R.12E. Associated minerals include beryl and biotite (WGNHS FILES).

WAUPACA COUNTY: Crystals of gadolinite-(Y) up to 4 cm. across have been recovered from a road cut in pegmatite cutting granite along County G near Keller Lake., NE of Big Falls. Associated minerals include euxenite-(Y), biotite, fluorite, K feldspar, bastnaesite group minerals, allanite and various sulfides. (Buchholz,Falster, Simmons and Fountain 2004)

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