In the race to hoard lithium, a metal crucial for creating the batteries that power electric vehicles, the US may have fortuitously stumbled on the world's biggest deposit yet.

A new study, published in the journal Science Advances, estimates that the McDermitt Caldera, a volcanic crater on the Nevada-Oregon border, harbors a colossal 20 to 40 million metric tons of lithium.

Based on these newest figures, the caldera dwarfs the amount of lithium in even Bolivia's salt flats, home to around 23 million tons.

"If you believe their back-of-the-envelope estimation, this is a very, very significant deposit of lithium," Anouk Borst, a geologist at KU Leuven University who was not involved in the study, told Chemistry World. "It could change the dynamics of lithium globally, in terms of price, security of supply and geopolitics."

Here to Clay
Some of the world's richest lithium stores are contained in brine. But the McDermitt Caldera's lithium, particularly in its southern portion in Nevada, in an area called Thacker Pass, is locked up in clay.

The caldera formed after a massive magma eruption approximately 16.4 million years ago, dredging up untold scores of lithium and other metals. A lake eventually inhabited the caldera, which deposited a layer of sediment spliced with the lithium that today is over 600 feet deep. The result: a clay called smectite.

But that was just the first lithium injection. Eventually, as volcanic activity heated up again, hot brine containing additional lithium was driven up into the existing smectite, infusing it with even more of it.

Now, the clay was no longer just smectite, but a uniquely lithium-rich illite.

"They seem to have hit the sweet spot where the clays are preserved close to the surface, so they won't have to extract as much rock, yet it hasn't been weathered away yet," Borst told Chemistry World.

Divisive Impact
This is good news for miners. Not only is this particular illite more rich in the metal, it's supposedly easier to separate. Plus, the deposits are mostly concentrated in one spot at the southern tip of the pass, limiting the area impacted by mining.

At least in theory. The extraction of lithium can, depending on the methods used, emit vast amounts of CO2, contaminate groundwater with dangerous heavy metals, and guzzle tons of fossil fuels. Its environmental toll shouldn't be overlooked in the rush to green transportation infrastructure.

For these reasons, the project has been mired in controversy. Conservationists have tried to block mining in the area, believing it would violate environmental laws. They're joined by Native American activists, as Thacker Pass is considered sacred by some local tribes.

But a federal court struck down their appeals in July, and workers have now broken ground at the site this week.