America’s Forgotten Mining Waste Could Become a Strategic Weapon

Highlights

• America holds 13,904 million metric tons of mine tailings containing critical minerals like cobalt, gallium, and germanium—potentially transforming waste into strategic domestic resources.
• The real challenge isn’t mining: it’s processing. China controls 90% of global refining capacity, and the U.S. lacks the separation infrastructure to convert tailings into usable materials.
• Reprocessing tailings offers a dual benefit: recovering strategic minerals for semiconductors, EVs, and defense while remediating environmental hazards from legacy mining sites.

America may already possess one of the world’s largest untapped critical mineral stockpiles—not in newly discovered deposits, but buried inside the waste of its own industrial past. In the April 2026 report (opens in a new tab) Critical-Minerals Recovery from Mine Tailings: A Technical Review and Strategic Assessment, lead author Robert Podgorney of Idaho National Laboratory and colleagues Travis McLing, Anthony Nickens, Shannon Bragg-Sitton, and John Wagner argue that billions of tons of historic U.S. mine tailings may contain recoverable rare earth elements (REEs), cobalt, gallium, germanium, indium, platinum-group elements, and other strategic minerals essential for semiconductors, AI infrastructure, defense systems, electric vehicles, and advanced energy technologies. The report frames these tailings not merely as environmental liabilities, but as a potentially strategic domestic resource that could strengthen American supply-chain resilience while simultaneously remediating polluted legacy mining sites.

The Waste America Left Behind

Mine tailings are the finely ground rock, slurry, and residual material left after miners extract primary commodities such as copper, gold, uranium, lead, or zinc. Historically, mining companies focused only on the metals economically valuable at the time. Many trace elements now deemed “critical minerals” were either technologically difficult to separate or commercially irrelevant decades ago.

According to the report, the United States contains an estimated 13,904 million metric tons of tailings across 189 major sites from just the top ten commodity categories alone. Arizona’s giant copper porphyry systems—including Sierrita, Bagdad, and Morenci—contain tailings enriched not only with residual copper, but also gallium, germanium, cobalt, and indium. Missouri’s historic lead-zinc districts contain tailings associated with neodymium, praseodymium, dysprosium, terbium, scandium, cobalt, and indium. The researchers compiled more than 300 datasets from over 100 organizations and repositories, representing over 10 gigabytes of information related to mine waste and critical mineral content.

The Real Bottleneck Isn’t Mining

The report repeatedly emphasizes a point REEx readers already understand well: America’s greatest vulnerability is not simply mineral extraction—it is processing.  In fact these authors have been thought leaders on the topic. Author Travis McLing has participated on the REEx podcast (opens in a new tab) a couple times.  McLing and colleagues know all too well that China dominates not only rare earth mining, but especially midstream refining and separation capacity. The report notes China controls roughly 90% of global rare earth processing capability. Even if the United States identifies enormous secondary mineral resources inside tailings, converting them into usable high-purity oxides, alloys, or metals requires sophisticated hydrometallurgy, solvent extraction, ion exchange, and refining infrastructure that America largely lacks today.

The study’s authors openly acknowledges that separation science—not geology—may be the hardest challenge.

Why Tailings Matter Strategically

Unlike greenfield mining projects, tailings already sit at the surface. Much of the expensive excavation, crushing, and grinding work has already been completed historically. In theory, this could lower energy use and operating costs relative to some new mines. The report also highlights an important dual benefit: reprocessing tailings could reduce acid mine drainage, heavy-metal leakage, dust pollution, and unstable impoundment risks while recovering strategic minerals.

For Washington policymakers increasingly focused on domestic supply security, this creates an unusually attractive political narrative: national security, industrial policy, and environmental remediation potentially aligned in one initiative.

The Catch: Enormous Barriers Remain

The report is ambitious but careful not to oversell the opportunity. Most U.S. tailings remain poorly characterized. The authors state fewer than 10% of datasets currently contain enough information to support immediate investment decisions. Many critical minerals exist only in trace concentrations, meaning massive volumes of material would still need to be processed economically.

The report also acknowledges severe barriers involving permitting, CERCLA liability exposure, environmental review timelines, geotechnical stability concerns, volatile commodity pricing, and the immense cost of multi-stage separation systems. The authors repeatedly call for federal subsidies, tax incentives, loan guarantees, government offtake agreements, and permitting reform to make many projects viable.

Importantly, the report is fundamentally a strategic and technical assessment—not a bankable economic feasibility study. It demonstrates potential resource opportunity, not guaranteed commercial success.

REEx Take

This report quietly reinforces one of the core themes REEx has emphasized repeatedly: the West’s critical mineral weakness is increasingly institutional and industrial—not merely geological.

America likely possesses far more recoverable strategic material than conventional narratives suggest. But discovering resources is only the beginning. The harder challenge is building the refining systems, chemical engineering capability, solvent extraction infrastructure, financing frameworks, workforce, and industrial coordination necessary to compete at scale.

Mine tailings may eventually become one of America’s most important secondary critical mineral frontiers. But unless the United States treats downstream processing and separation infrastructure with the same urgency as mining itself, these vast waste piles could remain exactly what they have been for decades: unrealized potential.

Citation: Podgorney R, McLing T, Nickens A, Bragg-Sitton S, Wagner J. Critical-Minerals Recovery from Mine Tailings: A Technical Review and Strategic Assessment. Idaho National Laboratory, April 2026.