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).