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The estimated $8.4 billion in U.S. rare-earth oxides is not a newly discovered mine or a proven reserve. It is a modeled estimate of potential value in coal ash—the waste left after coal is burned—in the Appalachian, Illinois, and Powder River basins. The figure accounts for assumptions about accessibility and extractability, but it does not represent money already recovered or a confirmed commercial opportunity.
Where is the estimated $8.4 billion resource?
The estimate concerns rare-earth elements in coal ash accumulated across three U.S. coal regions: Appalachia, the Illinois Basin, and the Powder River Basin in Wyoming. It is therefore a potential secondary resource in existing waste, not a newly identified underground ore body. The University of Texas at Austin’s Bureau of Economic Geology summarizes the estimate, citing a 2024 paper by Reedy and colleagues in the International Journal of Coal Science & Technology. Read the Bureau’s summary.
The Bureau summary reports coal-ash rare-earth concentrations of 585 parts per million (ppm) in Appalachia, 282 ppm in the Illinois Basin, and 330 ppm in the Powder River Basin. Those figures describe concentrations in ash; they do not by themselves show how much material can be recovered, or whether recovery would be profitable.
Does $8.4 billion mean the U.S. has a proven reserve?
No. “Reserve” can suggest a measured deposit that is economically recoverable under current conditions. The reported $8.4 billion is instead a modeled potential value for rare-earth oxides, with accessibility and extractability considered. It is not a current market quote, realized sales, or a sum that companies can necessarily recover. The sources reviewed do not establish commercial production, project-level extraction costs, or a current sales value.
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Important assumptions remain unclear in the available summaries, including the full valuation method, price-year and market basis for the oxides, and detailed site-by-site economics. Without those details, the figure is best read as an estimate of potential resource value—not as a forecast of revenue or a balance-sheet asset.
How much rare earth material is in the ash?
Published summaries do not present a fully consistent set of concentration figures. The Bureau of Economic Geology gives the basin figures above. A 2025 Thomasnet report instead gives 431 milligrams per kilogram (mg/kg) for Appalachian Basin ash and 264 mg/kg for Powder River Basin ash, and reports 70% extractability for Powder River Basin ash. See Thomasnet’s report.
These numbers should not be combined or treated as interchangeable without checking the underlying study and what each figure measures. The university summary and the trade article report different concentrations, and the available information does not resolve the discrepancy. The 70% figure is specifically attributed to Thomasnet’s report; it is not a universal recovery rate for coal ash or proof of commercial-scale extraction.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Can rare earth elements actually be extracted from coal ash?
Extraction is a subject of ongoing investigation, not an established commercial outcome for the resource described by the $8.4 billion estimate. Technical and economic barriers remain, and the reviewed sources do not establish an exact extraction process, commercial-scale output, or verified project cost. A concentration measurement alone cannot answer whether a particular ash deposit can be processed economically.
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University of Texas geologist and research professor Bridget Scanlon described the idea as “‘trash to treasure,’” but the appealing phrase does not remove the practical questions: which ash can be accessed, how much of its rare-earth content a process can recover, what it costs to do so, and what the recovered oxides would sell for. Read the science explainer.
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What the estimate tells readers—and what it does not
- It identifies a possible resource: coal ash in three major U.S. coal regions contains rare-earth elements that may have value.
- It is not a proven reserve: the $8.4 billion figure depends on modeling and assumptions about access and extraction.
- It does not establish a business case: the reviewed sources do not provide verified project costs, commercial production volumes, or realized sales.
- Concentration figures require care: the university summary and Thomasnet report different basin values, and the discrepancy is unresolved in the available material.
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