Rare Earth Element (REE), Critical Mineral, and Geochemical Characterization of Manganese Oxide Ore Deposits in the Appalachian Mountains of Tennessee, Virginia, and West Virginia

Manganese is a designated critical mineral, being industrially utilized for producing steel and batteries, including in the production of electric vehicles (Rozelle et al., 2021). The eastern United States hosts hundreds of manganese oxide mines that served steel production until their abandonment in the mid-twentieth century (Pegau, 1958). Many relict mines still feature accessible pits, waste rock, and unmined ore materials to varying degrees. Preliminary assessments of supergene manganese oxides in the Appalachian Mountains have revealed extensive enrichment in critical minerals and rare earth elements (REE) (Carmichael et al., 2017; Odom, 2020). The Appalachian Manganese Oxide Research Effort (AMORE) was established to: (1) characterize the location and extent of Appalachian manganese oxide mines using artificial intelligence mapping applied to high-resolution lidar elevation models and (2) assess the geochemical nature of remnant manganese oxide ore in the context of critical minerals. Here, we present geochemical data from 32 sites in Tennessee, Virginia, and West Virginia. Sampled materials include breccias with manganese oxide matrices, sandstones cemented by manganese oxides, quartzites with manganese oxide coatings, botryoidal nodules of manganese and iron oxides, and massive manganese oxides. The following concentrations are reported following an SiO2 content correction that assumes negligible REE enrichment in quartz. This correction was performed because some of these samples contained abundant quartz, which typically features extremely low concentrations of REE (Götze et al., 2023). Total REE content ranged from 35 ppm in a massive manganese oxide collected near Chattanooga, Tennessee to 4,351 ppm in a breccia collected near Vesuvius, Virginia. Morphological trends of total REE are evident in the median total REE for each sampled type: nodules (1,087 ppm), sandstone cements (1,019 ppm), quartzites (525 ppm), breccias (493 ppm), and massive manganese oxides (162 ppm). Cobalt, a superalloy and battery component, was notably high in breccias (median concentration = 4,531 ppm), nodules (median concentration = 2,624 ppm), and sandstone cements (median concentration = 1,367 ppm). Additional concentrated critical elements and their median concentrations across all morphologies include barium (21,439 ppm), zinc (2,501 ppm), nickel (604 ppm), lithium (93 ppm), arsenic (28 ppm), and beryllium (18 ppm). Ongoing work seeks to identify potential relationships between manganese oxide phase and critical element enrichment within given sample morphologies.

References

Carmichael, S. K., Doctor, D. H., Wilson, C. G., Feierstein, J., & McAleer, R. J. (2017). New insight into the origin of manganese oxide ore deposits in the Appalachian Valley and Ridge of northeastern Tennessee and northern Virginia, USA. GSA Bulletin, 129(9-10), 1158-1180. https://doi.org/10.1130/B31682.1
Götze, J., Pan, Y., & Müller, A. (2021). Mineralogy and mineral chemistry of quartz: A review. Mineralogical Magazine, 85(5), 639-664.
Odom, W.E. (2020). Dating the Cenozoic incision history of the Tennessee and Shenandoah Rivers with cosmogenic nuclides and 40Ar/39Ar in manganese oxides [Ph.D. dissertation]: West Lafayette, Indiana, Purdue University, 309 p., https://doi.org/10.25394/PGS.13275017.v1
Pegau, A.A. (1958). Virginia manganese minerals and ores, Virginia Division of Mineral Resources, Mineral Resources Circular No. 7.
Rozelle, P. L., Mamula, N., Arnold, B. J., O’Brien, T., Rezaee, M., & Pisupati, S. V. (2021). Secondary Cobalt and Manganese Resources in Pennsylvania: Quantities, Linkage with Mine Reclamation, and Preliminary Flowsheet Evaluation for the US Domestic Lithium-Ion Battery Supply Chain. The Pennsylvania State University, Center for Critical Minerals, University Park.