A remote stretch of land straddling the Nevada–Oregon border may be far more significant than it appears. According to new geological research, the McDermitt caldera—an expansive ancient volcanic crater—could contain between 20 and 40 million metric tons of lithium, putting it among the largest known lithium deposits on the planet.
Based on the recent U.S. contract price for lithium carbonate, roughly $37,000 per ton, the estimated value of the deposit runs into the trillion-dollar range, underscoring the potential impact this discovery could have on the global energy landscape. If developed, the site could become a major contributor to the supply chains that power electric vehicles, smartphones, and renewable-energy storage systems.
A Unique Geological Formation
The McDermitt caldera stretches approximately 28 miles from north to south and 22 miles from east to west. This enormous basin formed about 16 million years ago, when a powerful volcanic eruption emptied part of the underground magma chamber. As the chamber collapsed, it left behind a vast crater that gradually filled with layers of volcanic ash and sediment.
Research led by Thomas R. Benson, PhD, of Lithium Americas Corporation (LAC) has closely examined how the caldera’s geological structure trapped such an immense lithium reserve. After the initial eruption, ash deposits hardened into rock at the basin floor. Over the years, a lake developed within the crater, collecting fine ash and mud that later formed claystone layers. These layers became key to holding the lithium-rich minerals now attracting global attention.
How Lithium Became Concentrated in the Caldera
Long after the eruption ended, the magma beneath the caldera continued releasing hydrothermal fluids—hot, mineral-laden water that moved through underground fractures. These fluids dissolved lithium from volcanic glass deep below the surface and transported it upward into the lakebed sediments.
This process triggered a complex sequence of mineral transformations. The sediments first became smectite, a clay capable of absorbing lithium within its layers. Over time, with exposure to hotter fluids, parts of the smectite altered into illite, a potassium-based clay that traps significantly higher lithium concentrations.
At Thacker Pass, one of the most studied sections of the caldera, the illite layer forms a band almost 100 feet thick, lying close enough to the ground surface to be reached through open-pit mining. Studies have shown that this clay holds 1.3% to 2.4% lithium by weight, roughly twice the levels seen in typical claystone lithium deposits. Some analyses have even recorded concentrations around 1% by weight across parts of the basin, highlighting its unusually rich composition.
The fact that this high-grade material sits near the surface could dramatically lower mining costs and reduce the amount of waste rock typically generated in deeper operations.
Why This Discovery Matters for the Energy Transition
Lithium plays a central role in the global transition to clean energy. It is the backbone of lithium-ion batteries, which power everything from compact electronics to electric cars and large-scale grid storage systems that balance renewable energy sources like wind and solar.
Analysts estimate global lithium demand could reach one million tons per year by 2040, nearly eight times higher than production levels reported in 2022. This rapidly growing gap between supply and demand has prompted governments and companies to seek new, reliable deposits.
The McDermitt caldera stands out not only for its size but also for its accessibility. Because the clay-rich layers are shallow and laterally widespread, large-scale extraction would require significantly less energy and blasting than deep hard-rock mining. The combination of vast tonnage, high mineral grade, and favorable geometry makes this one of the most promising clay-hosted lithium resources ever documented.
Environmental and Cultural Questions Persist
The possibility of developing such a large-scale mining operation has drawn both interest and concern from local communities, including tribal nations and ranchers who rely on the region’s water sources and grazing lands. Environmental advocates have also raised questions about how mining could affect groundwater, wildlife habitats, and sensitive cultural landscapes.
Supporters of the project argue that harvesting lithium from a single, concentrated deposit may ultimately reduce environmental damage compared with operating multiple smaller mines elsewhere. They also point out that large claystone deposits tend to disturb less land per ton of lithium extracted.
Opponents counter that even a single massive open-pit mine can lead to groundwater depletion, dust pollution, and habitat fragmentation if not tightly regulated. They also stress that clay-hosted lithium is more complex to process, requiring extensive grinding and chemical leaching to extract the metal. This introduces additional concerns around water use and chemical waste management.
A New Blueprint for Finding Lithium in Volcanic Regions
The McDermitt discovery is reshaping how scientists understand the formation of major volcanic lithium deposits. Researchers now believe its exceptional concentration is linked to a specific set of geological conditions.
The magma that formed the caldera was peralkaline, meaning it was unusually rich in sodium and potassium—elements that help retain lithium during cooling. Later, during a phase known as resurgence, fresh magma rose beneath the caldera floor, cracking the rocks above it and creating channels for hot fluids to circulate. These conditions helped concentrate lithium-rich illite along the southern parts of the basin.
This emerging geological model is now guiding exploration teams as they search for similar volcanic-lake basins worldwide. However, only a handful of locations appear to match McDermitt’s rare combination of magma chemistry, closed-basin structure, and persistent hydrothermal activity.
