ASX-listed Pilbara Minerals has announced a 23% increase in contained lithium at its Pilgangoora operation in Western Australia, following a drilling campaign.

The updated mineral resource now stands at 446-million tonnes at 1.28% lithium oxide (Li₂O), 122 ppm tantalum pentoxide, and 0.59% iron oxide, containing 5.7-million tonnes of Li₂O and 120-million pounds of tantalum pentoxide.

The March 31, 2025 resource update reflects the results of a 104 672 m drill campaign, with 364 holes targeting down-dip extensions across a strike length of more than 7 km. This has led to a 39-million-tonne increase in total mineral resources and a 14% uplift in the measured and indicated category, which now stands at 376-million tonnes grading 1.29% Li₂O.

Pilbara Minerals MD and CEO Dale Henderson said the resource growth reaffirmed Pilgangoora’s position as one of the world’s largest and highest-quality hard rock lithium assets.

“This outcome is aligned with our strategy to optimise the operating base and unlock the full potential of this world-class asset, driving long-term value for our shareholders,” said Henderson. “It reflects the fundamental strengths of our business – large-scale, high-quality assets, disciplined operations, a diversified supply chain, and a strong balance sheet.”

A 12% increase in overall grade – from 1.15% to 1.28% Li₂O – is largely attributed to the addition of high-grade mineralisation in the Central Extension area and a revised assessment of reasonable prospects for eventual economic extraction, which removed lower-grade material from the prior estimate.

Despite scaling back exploration from the end of March as part of broader cost reduction efforts, Pilbara Minerals said mineralisation remains open along strike, including in the untested “Bridge Zone” between the Central and North areas, below 200 m depth.

The company noted that the updated resource accounts for four-million tonnes depleted by mining activity from July 2024 to March 2025.