Beneath a supervolcano, the world's largest lithium deposit is valued at $1.5 billion

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Under the ancient McDermitt crater, on the border between Nevada and Oregon, lies a huge lithium deposit, trapped in layers of volcanic clay.

According to a recent scientific analysis, the basin could contain between 20 and 40 million tonnes of lithium, a quantity likely to influence the entire battery sector for decades to come. Based on the average value of lithium carbonate in the United States, around $37,000 per tonne, this underground wealth would be worth almost $1,500 billion. An amount that has made this quiet, isolated region of the world a new focus of geopolitical attention.

Formation of the enormous lithium deposit

The fascination surrounding this lithium deposit and its complexity are rooted in its geological history. Nearly 16 million years ago, a colossal eruption emptied the entire underlying magma chamber, forming a vast caldera, a crater over 40 kilometres wide. Over time, the basin was transformed into a lake where volcanic ash and sediment accumulated. This material gave rise to thick layers of lacustrine clay, the ideal environment for trapping the lithium released by the subsoil.

A real turning point

The residual magma continued to release mineral-rich hydrothermal fluids: these boiling solutions filtered through the clay layers and changed their composition. First smectite was formed, a clay capable of absorbing lithium; then, at higher temperatures, the same smectite was transformed into illite, a potassium-rich variant containing much greater quantities of lithium.

At Thacker Pass, the most promising area, the illite layer is almost 30 metres thick and contains between 1.3% and 2.4% lithium by weight, almost double the values found in other clay deposits. Not an insignificant detail? This exceptionally rich layer is found at shallow depths, which means it can be mined by open-cast methods.

The future of batteries

Today, lithium is a key component of the rechargeable batteries that power our smartphones, laptops, electric cars and energy storage systems for renewable energies. According to experts, global demand could reach one million tonnes a year by 2040, around eight times the production of 2022. That's why such a concentration of lithium in a single region is attracting so much political and economic interest.

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Between energy opportunities and environmental concerns

The prospect of opening a mine on this scale raises concerns. Local communities, herders and indigenous tribes fear repercussions on water, ecosystems and sacred sites. Supporters of the project, on the other hand, argue that a single well-managed mine could have less impact than many small mines scattered elsewhere. Nevertheless, even one large pit can alter groundwater, disturb wildlife and generate dust.

In addition, extracting lithium from clays requires sophisticated technical steps: the rocks must be crushed, treated with chemical solutions and subjected to carefully controlled processes to recover the metal while limiting water consumption and waste.

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While the deposit is gigantic, it is also chemically unique, stratigraphically favourable and located in an inhabited region, where compromises between environmental protection and energy needs will be inevitable.

What is certain is that McDermitt has already revolutionised the way scientists and governments think about the distribution of critical minerals in volcanic systems. It is a powerful reminder that what illuminates our screens today and powers our electric motors often has its origins in geological events that took place millions of years ago.

Source: Science Advances

(©GreenMe.it/Managing Editor: Selma Keshkire - The Press Junction/Picture: Unsplash)