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Critical Minerals in Mine Wastes

There are tens of thousands of inactive or abandoned mine features in 274 mining districts in New Mexico (including coal, uranium, metals, and industrial minerals districts). Ore from these mines was processed at mills and smelters throughout the respective districts. However, many of these mills, tailings, slags, and smelters have not been inventoried, characterized, or prioritized for reclamation or reprocessing. Many of these mills, tailings, slags, and smelters have existing mine wastes, generated during mineral production, which could have potential for critical minerals, especially since the actual mineral production was generally for precious and base metals and not critical minerals. Therefore, any critical minerals that are found in a mineral deposit also could be found in the mine wastes (ore stockpiles, tailings, slags, etc.). Critical minerals are mineral commodities that are essential to the economic and national security of the U.S., and are from a supply chain that is vulnerable to global and national disruption (Committee on Critical Mineral Impacts of the U.S. Economy, 2008; Long et al., 2010; McLemore, 2011; McLemore and Gysi, 2023). Although some of these critical minerals are located in New Mexico, they have not been important exploration targets in the past because demand has been met economically elsewhere, mostly from China. However, with the projected increase in demand for critical minerals and the potential lack of available production from China and other countries, the New Mexico deposits including mine wastes are being re-examined for their critical mineral potential, and several areas of mill tailings are undergoing current exploration.

The purpose of this project is to 1) inventory mills, tailings, slags, ore stockpiles, and smelters in New Mexico, 2) populate a USGS ArcGIS database that documents the location of solid mine waste materials from these nonfuel processing sites in New Mexico, and 3) utilize a sampling and characterization procedure developed in collaboration with USGS personnel in mining districts in New Mexico to determine their critical mineral potential. The areal extent of these mine waste features must exceed 2000 m2. The USGS has provided an ArcPro template and sampling procedures that will be followed. Only information from public records will be inventoried.


The NMBGMR has been working on mine wastes since the 1950s. Several projects include the metals distribution of sediments along the Pecos River from the Pecos VMS mine (McLemore et al., 2001; Carey et al., 2001), effects of weathering on the stability of the mine rocks piles (dumps) at the Questa mine (McLemore et al., 2009 a,b, see reports below), an inventory and characterization of mine features and evaluation of mine wastes as part of the New Mexico AML project (see reports below), a study on uranium transport, uranium source characteristics, and uranium legacy issues in New Mexico (EPSCoR,, see below), a hydrologic assessment focused on the alluvial aquifer adjacent to the Animas River after the Gold King mine spill (Newton et al., 2017), and the effects of the Gold King mine spill on biota in the Animas and San Juan Rivers in north New Mexico (Duval et al., 2018; 2020). We are finishing up the EARTH MRI mine waste characterization study funded in 2023 and have presented papers and published preprints on work completed as of February 2024 (see reports below).

We also performed preliminary microbial characterization of an ephemeral, acidic seep at Copper Flat in June 2020, to collect inoculum for a leaching experiment. The pH and specific conductivity of the seep varied from 1.54-1.95 and 9.01-6.32 mS/cm, respectively. Based on rRNA gene libraries from nine exploratory samples, seep sediments were dominated by populations related to known lithotrophic iron-and sulfur-oxidizing bacteria (Leptospirillum spp., Ferrithrix spp., Acidibacillus spp.), diverse algae and acidophilic organoheterotrophs, and novel Proteobacteria and Thermoplasmatales-group Archaea that varied with the pH and salinity gradients in the seep.


Best, M.B., Jones, D.S., McLemore, 2024, Molecular assessment of metal-cycling microbial communities associated with critical mineral resources in historic mine waste: SME Annual Conference, presentation

Detsoi, B., Frey, B., McLemore, V., Jones, J., and Tsosie, R., 2024, Humates Used as a Filtering Medium for Uranium: SME Annual Conference, poster Won 2nd Place in the SME Environment Division Student Competition 2024

McLemore, V.T. and Owen, E., 2024, Geochemistry of Critical Minerals In Mine Wastes In New Mexico: SME Annual Conference, Preprint 24-043, 9 p., presentation

Motlagh, Z.K., McLemore, V., Newcomer, J., Griego, S. and Owen, E., 2024, Acid Mine Drainage and Critical Minerals in Black Hawk Mine Waste, Grant County, New Mexico: SME Annual Conference, Preprint 24-022, 7 p., presentation, poster

Serwah Acheampong-Mensah, A., and McLemore, V.T.,2024, Geochemistry of critical minerals in mine wastes at Hillsboro and Steeple Rock districts, New Mexico: SME Annual Conference, Preprint 24-042, 7 p., presentation, poster

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