Australian researchers have upended decades of geological theory, revealing that the world's richest hard-rock lithium deposits likely formed deeper in the Earth than previously thought.

The breakthrough, led by Curtin University and the Geological Survey of Western Australia (GSWA), proves those deposits developed closer to the mantle, not near the surface. 

The discovery could redefine how and where lithium is explored globally. It comes as demand surges for the critical mineral, used in batteries for electric vehicles, smartphones and renewable energy storage systems.

Professor Hugh Smithies, lead author and geologist with Curtin's Frontier Institute for Geoscience Innovation and GSWA, said the findings offer a new framework for understanding lithium formation. The research shows lithium-rich magmas likely formed when mantle-derived melts were remelted and channelled along deep fault zones, enriching ancient crustal rocks.

“This connection to deep mantle magmas and enriched crustal sources helps explain why WA's ancient terrains, which lack the sedimentary rocks long thought necessary, host some of the world's largest lithium deposits,” Smithies said. “It could expand exploration potential into previously overlooked regions.”

Australia leads

Western Australia already produces around 35% of the world's lithium, which is more than 1.5 times Chile's output, the next-largest supplier. 

Most of this comes from pegmatite, a coarse-grained igneous rock common in WA's Archean terrains, which are over 2.5 billion years old, like those in the Pilbara and Yilgarn regions.

While most hard-rock lithium is sourced from similar formations, current exploration models are largely based on younger geological systems. The GSWA's research challenges these models, showing that Archean lithium systems follow their own rules and depend on a unique set of deep-earth processes.

The new findings suggests that Archean lithium systems follow distinct rules and require a unique set of geological features for the formation of these deposits.

The study's findings, published in Nature, arrive at a pivotal moment. As lithium demand continues to climb, the authors say this new understanding could reshape exploration strategies – not just in Western Australia, but worldwide.