McDermitt Caldera holds 44 million tons

The McDermitt Caldera is a giant volcanic bowl on the Nevada-Oregon line, and it matters because a lot of America’s lithium hopes are now pinned to it. That is the battery metal used in EVs and grid storage. The gap is that the U.S. wants more domestic supply, but most lithium still comes from abroad and the easiest deposits are already spoken for. What changed is not some brand-new discovery today — it is that the caldera’s biggest known project, Thacker Pass, kept moving toward production in 2025 and 2026, while new exploration on the Oregon side also moved into federal review. ### Where does the “44 million tons” claim come from? It mostly comes from a real number that got flattened in social media. Lithium Americas updated its technical report for Thacker Pass in January 2025 and said the project holds 44.5 million tonnes of lithium carbonate equivalent, or LCE, in measured and indicated resources. That is not the same thing as 44 million tonnes, smaller than the headline makes it sound. ### So is McDermitt still unusually big? Yes. Even after you strip away the social-media inflation, McDermitt still looks enormous. USGS and recent geology papers describe the caldera as hosting one of the world’s largest lithium accumulations, with lake sediments laid down inside a 16.4-million-year-old volcanic collapse structure. The southern end — where Thacker Pass sits — is the best drilled and best defined so far, which is why the hard numbers come from there first. ### Why is this deposit different? Because this is not the classic image of lithium coming from a salty brine pond or a hard-rock spodumene mine. McDermitt is a claystone deposit. The key twist is that hot, lithium-rich fluids later altered those sediments and concentrated lithium into illite-rich zones. That is why some samples at Thacker Pass reach about 1 weight % lithium — strikingly high for clay-thermal fluids upgraded the ore. ### Why does that excite miners? Scale and location. Clay deposits can be shallow and laterally extensive, which can mean lower strip ratios than some hard-rock mines. And this one is in the United States, near a battery supply chain Washington has been trying to build at home. Lithium Americas says Thacker Pass Phase 1 is designed for 40,000 tonnes a year of battery-grade lithium carbonate, with mechanical completion targeted for late 2027. ### Why is extraction the hard part? Because clay is chemically awkward. Lithium in clay is not sitting there ready to evaporate out of brine. You have to mine the rock, process huge volumes of material, and use acid or other chemical steps to get the lithium out at scale. A giant in-ground resource is not the same thing as a giant profitable reserve. Even at Thacker Pass, the proven and probable reserve is much smaller than the broader resource number that gets shared online. ### What is happening on the Oregon side? Federal land managers opened a public comment process in March 2025 for HiTech Minerals to drill 267 exploration sites across 7,200 acres of public land in Malheur County, Oregon. That does not mean a mine is approved. It means companies are still trying to figure out how much lithium is there, where the richest zones sit, and whether the economics work outside the Nevada side’s better-known footprint. ### Why is the project so contested? Because the tradeoff is real. The caldera overlaps sensitive habitat, water concerns, and sites important to tribes and local communities. A 2026 academic paper on McDermitt framed the conflict bluntly — the U.S.’s largest suspected lithium deposit sits under a landscape many people do not want industrialized. That tension is not a side issue. It is the story. ### Bottom line? McDermitt is probably one of America’s most important lithium districts. But “44 million tons of lithium” is a sloppy version of the real figure. The resource is huge, the geology is remarkable, and the industrial promise is obvious — but turning volcanic clay into battery chemicals without blowing up the surrounding landscape is still the part nobody gets to skip.