Highlights

• Indiana's comprehensive audit identifies $5-6 billion in critical minerals locked in coal ash and waste streams, with some samples exceeding DOE's 300-ppm economic threshold.
• Despite 80-90% lab recovery rates, no commercial-scale coal-derived REE operation exists globally—technology remains unproven beyond the pilot phase.
• The state's strongest opportunity lies in pairing mineral recovery with mandated AMD remediation, requiring new regulatory frameworks beyond existing waste management rules.

---

Indiana’s December 2025 report, Indiana’s Opportunity in Rare Earth Elements and Critical Minerals (opens in a new tab), is one of the most comprehensive state-level audits yet of coal-derived critical mineral potential. Prepared by the Indiana Geological and Water Survey (opens in a new tab) with funding from the U.S. Department of Energy, the study is notable less for hype than for its restraint. It inventories what exists, what might be recoverable, and—crucially—what remains unproven.

The headline finding is straightforward

Indiana’s coal legacy has left behind enormous volumes of already mined material—coal ash, coal preparation waste, acid mine drainage (AMD), paleosols, and black shales—that contain rare earth elements (REEs) and other critical minerals. In a geopolitical environment dominated by China’s control of roughly 70% of global REE supply and close to 90% of processing capacity, these unconventional sources are strategically interesting.

Where the Data Are Strong

Coal ash emerges as the most credible near-term feedstock. Indiana produces roughly five million tons annually, and legacy impoundments contain tens of millions more. Laboratory analyses show REE concentrations frequently exceeding the Department of Energy’s 300-ppm economic screening threshold, with some samples reaching 700–900 ppm.

The report estimates $5–6 billion in theoretical REE value locked in coal ash and slurry deposits, driven largely by scandium, neodymium, dysprosium, and terbium.

Coal preparation waste and AMD add a second tier of opportunity. AMD is particularly notable because REEs are already dissolved in solution, meaning recovery could be paired with mandated environmental remediation. This “recover-while-cleaning” model is one of the report’s most defensible concepts and aligns with prior DOE-funded pilot work in Appalachia.

Paleosols and black shales round out the resource base. While REE grades are generally lower, the report identifies potentially economic concentrations of gallium, germanium, vanadium, zinc, and lithium—supporting a co-production strategy rather than a single-metal bet.

Technology: Feasible in Theory, Unproven at Scale

The report is explicit—and _Rare Earth Exchanges_™ agrees—on a critical point: to date, there is no substantive evidence that coal-derived rare earth recovery has succeeded at sustained commercial scale.

Recovery pathways are technically well understood. Laboratory and pilot studies demonstrate 80–90% recovery rates using combinations of roasting, alkali or acid leaching, solvent extraction, ion exchange, and newer approaches such as ligand-assisted chromatography and bio-leaching. But almost all supporting data come from bench-scale or short-run pilots.

No large, continuous, economically self-sustaining coal-derived REE operation currently exists in the United States or globally. Chemical costs remain high, separation is complex, and scaling introduces nonlinear challenges that small pilots cannot resolve. Investors should treat recovery percentages as technical ceilings, not commercial guarantees.

That said, even critics of coal-based REE recovery remain open to the next generation of pilots, particularly those that (a) integrate co-products, (b) leverage AMD remediation mandates, and (c) operate at sufficient duration and throughput to generate credible cost curves.

Regulation: Predictable, but Incomplete

Indiana benefits from regulatory maturity. Oversight by the Indiana Department of Environmental Management and the Indiana Department of Natural Resources provides clarity for coal refuse and coal combustion residuals. However, those frameworks were built for waste management, not resource recovery.

REE extraction introduces new chemical processes, new residues, and new risks. The report rightly flags permitting uncertainty as a deterrent to private capital and calls for pilot-specific guidance, coordinated permitting, and regulatory sandboxes.

The Strategic Reality Check

Indiana is not positioning itself as the next Mountain Pass. Instead, the report makes a narrower—and more credible—claim: the state holds a portfolio of secondary, already-mined resources that merit structured experimentation.

The path forward is not scale-up by decree. It is disciplined pilot work, transparent cost accounting, regulatory clarity, and a willingness to conclude—if the data demand it—that some pathways will not clear economic hurdles. Coal-derived rare earths remain an open question. Indiana’s contribution is to ask that question rigorously.

© 2025 Rare Earth Exchanges™ – Accelerating Transparency, Accuracy, and Insight Across the Rare Earth & Critical Minerals Supply Chain.