The United States possesses significant reserves of rare earth elements (REE), which are crucial for modern industries, including electronics, defense systems, and renewable energy technologies. Due to the increasing global demand and concerns over foreign dependency, domestic exploration and development of REE resources have become a strategic priority. This document provides a detailed analysis of the mineralogy, current sources, and domestic reserves of REE deposits in the United States.
The Mountain Pass mine in California is the only fully operational REE mine in the United States. It is a world-class deposit with proven and probable reserves of approximately 13.6 million metric tons, containing an average grade of 8.24% total rare earth oxides (TREO) and around 1.12 million metric tons of contained REE oxides. Mountain Pass has been extensively explored and developed, making it the leading domestic source of REEs.
Apart from Mountain Pass, several other deposits across the U.S. are in different stages of exploration and assessment. These deposits, though significant in scale, require further feasibility studies and development efforts before they can contribute to domestic supply.
The U.S. Geological Survey, in collaboration with evaluations from the private sector, has identified several rare earth element (REE) deposits throughout the country. These deposits have been classified based on the level of exploration and their economic viability into proven and probable reserves, as well as inferred resources.
Among the proven and probable reserves is the Mountain Pass deposit located in California, which contains approximately 13.6 million metric tons of material with a total rare earth oxides (TREO) concentration of 8.24%. This equates to about 1.12 million metric tons of rare earth oxides.
In terms of inferred resources, there are notable deposits that show promising potential for future development. For instance, the Bear Lodge deposit in Wyoming holds around 25 million metric tons at a TREO concentration of 2.64%, which translates to approximately 659,500 metric tons of rare earth oxides. Additionally, the Bokan Mountain deposit, particularly in the Dotson and I&L Zones located in Alaska, contains an estimated 6.7 million metric tons at a TREO concentration of 0.58%, equating to about 38,900 metric tons of rare earth oxides.
Numerous sites across the United States contain rare earth element (REE) mineralization, although limited exploration has left their economic viability uncertain. Among the notable deposits is Iron Hill in Colorado, which boasts an impressive 2.42 billion metric tons of material with a total rare earth oxide (TREO) concentration of 0.40%, yielding around 9.7 million metric tons of rare earth oxides. In Alaska, Bokan Mountain presents a smaller yet significant deposit of 34.1 million metric tons at a concentration of 0.48% TREO, which translates to approximately 164,000 metric tons of rare earth oxides.
Missouri's Pea Ridge site stands out with a remarkable TREO concentration of 12%, totaling 600,000 metric tons and containing about 72,000 metric tons of rare earth oxides. Meanwhile, Mineville in New York offers 9 million metric tons at a concentration of 0.9% TREO, contributing around 80,000 metric tons of rare earth oxides as well. In addition to these, there are other deposits located in Idaho, New Mexico, Wyoming, Illinois, and various other states, each showcasing a range of REE concentrations.
Although the United States has substantial REE resources, many of these deposits remain underdeveloped due to economic challenges, regulatory hurdles, and the high costs of processing. Mountain Pass is the only active REE mining operation, but its refining and processing capabilities are limited compared to global competitors, particularly China, which dominates the REE supply chain.
To establish a more self-sufficient domestic supply chain, further investments in exploration, extraction technology, and processing facilities are necessary. Increased funding and policy support for REE production could enhance national security and reduce reliance on foreign sources.
The long-term supply of REEs in the United States will depend on continued exploration and development of existing deposits, as well as the discovery of new mineralized zones. The U.S. government and private industry must collaborate to advance REE mining projects while addressing environmental and regulatory concerns.
With increasing global demand for rare earth elements (REEs) in high-tech applications, the development of domestic processing infrastructure and supply chains will be crucial for maintaining economic competitiveness and national security.
The United States has vast REE mineral resources, but only a fraction has been developed into operational mines. Mountain Pass remains the sole major REE producer, while numerous other deposits have significant potential for future exploitation. By investing in geological research, mining technologies, and refining capabilities, the U.S. can strengthen its position in the global REE market and ensure long-term resource security.
Long, K. R., Van Gosen, B. S., Foley, N. K., & Cordier, D. (2012). The Principal Rare Earth Elements Deposits of the United States: A Summary of Domestic Deposits and a Global Perspective. Non-Renewable Resource Issues, 131–155. doi:10.1007/978-90-481-8679-2_7