WGNHS
Wisconsin Geological and Natural History Survey

Thalenite-(Y)

Etched-appearing masses of thalenite-(Y) on K feldspar, associated with xenotime-(Y). From Koss Pit, Marathon County, Wisconsin. (Photo and specimen from Tom Buchholz.)

Formula: Y3Si3O10(OH) Monoclinic

Description:

Thalenite-(Y) is a rare mineral found as pinkish, greenish or brownish grains in complex pegmatites.

MARATHON COUNTY: Thalenite-(Y) has been documented as occurring as rare grains in pegmatites in the Koss Pit, a large “rotten granite” quarry in the SW sec. 2 T.27N. R.5E. (Buchholz et. al., 2001).