PRIORITIZATION OF LEGACY MINE SITES FOR WORK: THE LARGEST PAST PRODUCERS OF BASE METALS, PRECIOUS METALS, AND CRITICAL MINERALS IN THE US

World-class and significant deposits host a disproportionate percentage of Earth’s metal endowment. The Infrastructure Investment and Jobs Act of 2021 directs the USGS’ Earth Mapping Resources Initiative to map and collect data for areas containing mine waste to increase understanding of above-ground critical mineral resources in previously disturbed areas. To help prioritize legacy mine sites for work, the USGS Mineral Deposit Database Project (USMIN) has compiled a list of the 75 deposits or districts in the U.S. that are the largest past producers of Cu, Zn, Pb, Ag, Au and the critical minerals Co, Ga, Ge, graphite, Li, Nb, REE, Te, Sn, and W. This list includes 21 different deposit types: brine (n=2), carbonatite (n=1), Carlin (n=2), epithermal (n=1), flake graphite (n=6), greisen (n=1), intermediate-sulfidation epithermal (n=2), Keweenaw Cu (n=1), Kipushi (n=1), magmatic hydrothermal replacement (n=4), Mississippi Valley (n=8), non-sulfide zinc-lead ± Mn (n=1), orogenic (n=5), pegmatite (n=6), placer (n=9), porphyry (n=10), replacement polymetallic (n=1), sediment-hosted massive sulfide (n=4), skarn (n=6), vein (n=4), and vein graphite (n=1). These deposits or districts occur in 27 states with significantly different climate and vegetation cover: Alaska (n=10), Alabama (n=2), Arizona (n=6), California (n=7), Colorado (n=7), Florida (n=1), Idaho (n=4), Illinois (n=1), Iowa (n=1), Kansas (n=1), Michigan (n=1), Missouri (n=5), Montana (n=2), North Carolina (n=3), New Jersey (n=1), New Mexico (n=1), Nevada (n=7), New York (n=2), Oklahoma (n=1), Pennsylvania (n=2), South Dakota (n=4), Tennessee (n=1), Texas (n=1), Utah (n=4), Virginia (n=1), Wisconsin (n=1) and Wyoming (n=3). This compilation provides a diverse list of mineral deposits with significant past production that can help prioritize and select legacy mine sites for future work. Furthermore, because approximately half of the 50 critical minerals in the U.S. occur as byproducts (e.g., As, Bi, Ga, Ge, In, and Te), and the majority of those are recovered from base metal deposits, this compilation also helps prioritize mine waste sites that may contain significant endowments of byproduct critical minerals that were not reported or recovered in the past.