Minerals, such as monazite and xenotime, are an important source of rare earth (La, Ce, Nd) and high field strength (Th, Nb, Zr) elements which are essential for modern energy, communication, and military technologies. These critical minerals are often sourced in pegmatites associated with alkalic complexes, such as mines at Mountain Pass, USA, and Mount Weld, Australia. The Paleoproterozoic Eau Claire Volcanic Complex is intruded by granitic pegmatite dikes that postdate peak metamorphism, potentially linking them to 1.7 to 1.4 Ga fractionated alkalic magmas in the region. These pegmatites are highly fractionated, garnet-bearing, and low in calcium. The high concentration U, Th, La, Ce, and other rare earth elements put this pegmatite in niobium-yttrium-fluorine (NYF) class of pegmatites. This study collected bedrock samples from several locations across the Eau Claire Volcanic Complex (Little Falls, North Fork, Muskeg) to describe the trace mineral compositions. The minerals in the pegmatite samples were geochemically analyzed using a scanning electron microscope energy-dispersive X-ray spectrometer (SEM-EDS). The major minerals in the samples are mainly plagioclase, quartz, and biotite. They contain minor mineral chemistry of Fe- and Mn-garnets, samarskites, xenotimes, monazites, thorites, and barites and may represent a potential source for critical minerals in Wisconsin.
