Canadian company Lithium Americas began construction on a new mine in Nevada’s Thacker Pass, sparking violent protests among local residents and environmentalists. But that’s just the beginning, as the site is part of the remnant of a massive supervolcano that hides one of the world’s largest deposits of lithium. Understanding how it got there can determine where mining companies look for this valuable resource next.

Lithium at the bottom of the volcano

Lithium Americas has published a new study showing that lithium is distributed over 600 square miles between Nevada and Oregon. Thacker Pass, where the particularly high-quality material is located, is near the southern end of this region, called the caldera.

The company is looking for a clay mineral called illite, which has twice the lithium concentration of the more common smectite. How the illite got there is a great mystery; If resolved, it could help find where other lithium reserves are hiding.

The study, published in the journal Science Advances, seeks to understand what is so special about this volcano, which exploded and collapsed about 16 million years ago, leaving behind a crater filled with lithium-rich smectite clay. Previous studies suggest that lithium first leached from volcanic glass and accumulated in the caldera. But that doesn’t explain how illite forms with a surprisingly high lithium concentration.

To trace their origin, the research team analyzed chemical compounds in three core samples taken from the southern part of the caldera. Scientists say that after the destruction of the volcano, there is a process called hydrothermal enrichment. Magma moving below the surface pushed up the center of the caldera, forming what is now the Montana Mountains. This movement also created faults and cracks. Fluid from the magma chamber flowed through these faults, bringing more lithium to the surface and converting smectite to illite along the southern edge of the basin.

What’s really special about this deposit is that there are already huge reserves of lithium available when there’s a massive influx of all this lithium-rich liquid causing the massive over-enrichment of lithium.
– says the article.

So far, scientists believe there is insufficient evidence to say definitively that this particular event occurred millions of years ago and is responsible for the high-grade ore at the McDermitt volcano site. “Some of the evidence is actually pretty weak. For example, the movement that created the Montana mountains also left faults in the northern part of the caldera. So if the hypothesis is correct, the illite must be there as well.”. But for some reason it is concentrated in the southern region and Lithium Americas will open its next mine there.

Company representatives say they want to minimize the amount of material removed from Earth as it can no longer be brought back. This requires the most concentrated rocks such as illite.