WGNHS
Wisconsin Geological and Natural History Survey

Tapiolite Series

Crystals of intergrown tapiolite series minerals. Both Fe- and LREE-rich tapiolite crystals are likely present. From Koss Pit, Marathon County, Wisconsin. SEM photograph. (Image and sample from Tom Buchholz.)

Formula: (Fe,Mn)(Ta,Nb)2O6 - (Mn,Fe)(Ta, Nb)2O6 Tetragonal

Description:

Tapiolite-(Fe), Koss Pit, near Wausau, Marathon County, Wisconsin (Photo by Al Falster.)

A series exists between ferri-tapiolite and manganotapiolite. These rare minerals are found in complex granite pegmatites.

MARATHON COUNTY: A member of the tapiolite series is found as rare small black masses in pegmatites at the Koss Pit (SW sec. 2 T.27 N. R.5E.) SW of Rib Mountain. (Buchholz, Falster and Simmons, 1999, 2000)