Found: One of the Largest Potential Lithium Deposits on the Planet

At first glance, the McDermitt Caldera might feel like the edge of the Earth. This oblong maze of rocky vales straddles the arid Nevada-Oregon borderlands, in one of the least densely populated parts of North America.

But the future of the modern world depends on the future of places like the McDermitt Caldera, which has the potential to be the largest known source of lithium on the planet. Where today’s world runs on hydrocarbons, tomorrow’s may very well rely on the element for an expanding offering of lithium-ion batteries. The flaky silver metal is a necessity for these batteries that we already use, and which we’ll likely use in far greater numbers to support mobile phones, electric cars, and large electric grids.

Which is why it matters a ton where we get our lithium from. A new study, published in the journal Science Advances today, suggests that McDermitt Caldera contains even more lithium than previously thought and outlines how the yet-to-be-discovered stores could be extracted. But these results are unlikely to ease the criticisms about the environmental costs of mining the substance.

By 2030, the world may require more than a megaton of lithium every year. If previous geological surveys are correct, then the McDermitt Caldera—the remnants of a 16-million-old volcanic supereruption—could contain as many as 100 megatons of the metal.

“It’s a huge, massive feature that has a lot of lithium in it,” Tom Benson, one of the authors of the new paper and a volcanologist at Columbia University and the Lithium Americas Corporation.

One high-profile project, partly run by Lithium Americas Corporation, proposes a 17,933-acre mine in the Thacker Pass, on the Nevada side of the border at the caldera’s southern edge. The project is contentious: Thacker Pass (or Peehee Mu’huh in Northern Paiute) sits on land that many local Indigenous groups consider sacred. Native American activists are continuing to fight a plan to expand the mine-exploration area in court.

But not all of the lithium under McDermitt’s rocky sands ranks the same. Most of the desired metal there comes in the form of a mineral called smectite; under certain conditions, smectite can transform into a different mineral called illite that can sometimes also be processed for lithium. Benson and his colleagues studied samples of both smectite and illite drilled from the ground throughout the caldera. “There’s lithium everywhere you drill,” he says.

Previously, geologists assumed that you could find both smectite and illite in a wide distribution across the caldera, but the authors only found the latter in high concentrations in the caldera’s south, around Thacker Pass. “It’s constrained to this area,” explains Benson.

That’s important. Benson and colleagues think that the caldera’s illite formed when lithium-rich fluid, heated by the underlying volcano, washed over smectite. In the process, the mineral absorbed much of the lithium. Consequently, they project the illite in Thacker Pass holds more than twice as much lithium than the neighboring smectite.

by Rahul Rao, PopSci | Read more:
Image: Carolyn Cole / Los Angeles Times via Getty Images
[ed. Funny how we seem to find just what we need when we need it.]