From data to drill rigs: how Jupiter became Australia’s biggest clay rare earth discovery and a model for finding the next generation of critical minerals

When a geologist looks at a gravity anomaly and sees the future of Australia’s critical minerals, it’s worth paying attention. That’s exactly what Dr Natalee Bonnici, senior exploration geologist at Critica Limited (formerly Venture Minerals), and her team did when they began chasing a hunch west of Mount Magnet. Less than two years later, they had delivered a discovery that redefined the country’s rare earth potential: the Jupiter deposit, now the largest and highest-grade clay-hosted REE resource in Australia.

From data to discovery

The Jupiter story began not in the field but behind a screen. “We were extremely lucky in Australia to have an enormous amount of public data freely available to generate new targets,” Natalee explained at the AusIMM Critical Minerals Conference 2025 in Perth. The team tapped into open-file datasets from Geological Survey WA, Geoscience Australia, and CSIRO’s laterite geochemistry database, zeroing in on one standout sample showing 18,164 ppm REEs – the third-highest value in the dataset.

Armed with geophysics and geochemistry, Critica’s explorers followed coincident aeromagnetic highs and gravity anomalies, aiming first for a carbonatite-style system. “When the drilling returned granitic basement, the ground was nearly dropped,” Natalee laughed. “But when the assays came back with 49 metres at 1,300 ppm TREO, we knew we were onto something significant.”

A resource that grew fast

Momentum built quickly. By the end of 2024 – barely a year after discovery – the team had completed 625 aircore and seven diamond holes, mapping a 4.5 km-wide, clay-hosted mineralised system continuous across the entire anomaly. In February 2025, Critica announced its maiden inferred resource: 1.8 billion tonnes at 1,700 ppm TREO, including 520 million tonnes at 2,200 ppm high-grade material.

The scale and grade immediately placed Jupiter ahead of better-known peers such as Splinter Rock and North Stanmore. “We knew we had something special,” said Natalee. “Thick, consistent mineralisation, low uranium and thorium, and it’s right here in Western Australia.”

The science beneath the success

What sets Jupiter apart isn’t just its size – it’s the mineralogy. “For rare earth deposits, mineral speciation is critical because it determines whether you can extract and recover the elements,” Natalee said. Detailed TIMA, EPMA and laser ablation analyses revealed REE mineralisation hosted in rare earth phosphates, including goyazite, gorceixite, florencite, rhabdophane, and monazite, all favourable for leaching and recovery.

Equally important, the REE mineralogy remains consistent throughout both the upper and lower saprolite. “That’s a huge advantage,” she said. “The mineralisation doesn’t change, so that’s one less thing we have to worry about. It gives us confidence in how we design our metallurgy.”

Gangue minerals – chiefly kaolinite, feldspar, albite, iron oxides, and quartz – reflect subtle changes in the underlying fresh rock, leading the team to an even bigger revelation: the basement beneath Jupiter wasn’t what anyone thought.

A geological surprise

“As the project developed, it became clear that the underlying basement was not part of the Big Bell Suite as it had been mapped,” Natalee said. Diamond core and lithogeochemical analysis instead revealed a previously unrecognised alkaline intrusive complex – a zoned body of alkali gabbro, syenodiorite, syenite, and quartz monzonite – now named the Jupiter Intrusive Complex.

“This complex doesn’t outcrop, so no one had seen it before,” she noted. “It formed through the differentiation of an alkali gabbroic magma intruding into a monzonitic granite batholith – and it’s incredibly REE-anomalous.” In effect, the deposit represents a weathered, supergene-enriched cap over a buried alkaline intrusion, providing a new exploration model for similar terrains.

Lessons for explorers

For exploration professionals, Jupiter’s discovery offers a masterclass in combining open data, targeted drilling, and advanced mineralogical analysis. “We started with public datasets, validated them with geophysics, and built from there – no shortcuts,” said Natalee. “The consistency of the mineralisation and its recoverability have given us a clear pathway to development.”

The broader significance goes beyond Critica’s portfolio. Jupiter confirms that large, low-thorium, high-grade, clay-hosted REE systems can exist entirely beneath cover in Australia – and can be found and defined within an exceptionally short timeframe using disciplined, integrated exploration.

As Natalee summed up, “It’s been an enormous effort from the whole team, but what’s most exciting is what it means for Australia’s critical minerals future. We’ve shown that world-class rare earth discoveries are not just possible here – they’re already happening.”

In short: Jupiter’s rise is more than a story of data, drilling, and determination – it’s proof that Australia’s next generation of rare earth discoveries may be hiding in plain sight beneath its ancient regolith.