The Voyageur lands cover a diverse assemblage of Proterozoic sedimentary and volcanic rocks that have the potential to host a variety of mineral deposit types, including magmatic nickel, copper, PGM, and orogenic gold. Despite the extensive history of copper and iron mining in the western Upper Peninsula of Michigan, the Voyageur Lands are at a relatively early stage of exploration.
Within the Voyageur lands, Bitterroot has identified significant potential for PGM mineralization in the 35 square-kilometre Echo Lake layered mafic intrusion. In 1997, Bitterroot drilled 3,270 meters in five core holes at Echo Lake. Drill hole EL-97-03 intersected ten flat-lying anomalous PGM-bearing horizons within the intrusion, with the highest-grade interval containing 1.01 grams Pt+Pd+Au/tonne over 5.42 metres (17.8 feet), within a 21.3 metre (69.8 feet) interval grading 0.52 grams Pt+Pd+Au/tonne. The Echo Lake intrusion has potential to host additional reef-type PGE mineralization along strike from the currently known mineralized zones and Ni-Cu-PGE mineralization along its contacts or within satellite intrusions and feeder dykes.
Lundin Mining's Eagle nickel/copper/PGM deposit is located in a Keweenanwan-aged (~1.1 billion year-old) mafic intrusion in the Paleoproterozoic (~1.85 billion year-old) Michigamme Formation. This geological setting also occurs under much of Bitterroot's Voyageur Lands. Rio Tinto has recently conducted drilling and land acquisition activities targeting Eagle-type ore deposits on lands adjoining Bitterroot's Voyageur Lands. Several of Rio Tinto's 2012 drill collars are located within 180 metres of Bitterroot's mineral rights. Geophysical work in this particular area has resulted in the identification of several high-priority targets that Bitterroot drill-tested in 2014. Additional drilling is planned.