What Jupiter’s Rare Earth Purity Leap Signals for Australian Mining

Critica Limited has taken the rare earth oxide product from its Jupiter project from roughly 84% purity to 98.2% in under a year of testwork, a trajectory that would have looked optimistic when the program began. On 23 September 2026, the company reported that latest figure, the highest yet.

That number arrives at a telling moment. A Scoping Study led by engineering firm Sedgman is expected to complete during Q3 2026, which is when laboratory results have to start becoming an economic case. Jupiter is also clay-hosted, a style of rare earth deposit most Australian investors will not have encountered in any depth, and that distinction shapes everything about how the project would be built and what it would cost.

Here is what the purity numbers actually signal, how clay-hosted processing works, and which specific milestones will tell you the most about whether this project can make the leap from bench to mine. You will leave with a working mental model of the deposit, the flowsheet, and the risks that sit alongside the progress.

What makes a clay-hosted rare earth deposit different from everything else

Rare earth deposits are not all cut from the same rock, and the differences matter more than most coverage suggests. How the rare earth elements are physically held inside the host material determines how you get them out, and that in turn determines the cost of the entire operation.

There are three broad classes worth knowing.

• Hard-rock deposits (carbonatites and monazite systems such as Lynas Rare Earths’ Mt Weld and Arafura’s Nolans): typically higher head grades, but the rare earths are locked in dense minerals that need mining, crushing, grinding, and aggressive chemical cracking to release. That drives high capital cost and high energy use.
• Ionic clay deposits (widespread in China): rare earths sit loosely adsorbed on clay surfaces, so they can be leached out at ambient conditions with relatively simple chemistry. Historically low capital cost and strong margins for heavy rare earths, though the International Energy Agency and Adamas Intelligence have both flagged their well-documented environmental impacts.
• Non-ionic clay-hosted deposits (Australia, Brazil, parts of Africa): grades are moderate, but processing can lean on physical upgrading and selective leaching rather than full hard-rock comminution. Analysts at Wood Mackenzie and Benchmark Mineral Intelligence note these can offer lower capital intensity than hard-rock peers, if the beneficiation works.

Jupiter falls into that third category. It is non-ionic clay-hosted, which distinguishes it from the Chinese ionic clay systems and places it in a deposit class that is newer and carries far less commercial track record.

The economics of clay-hosted deposit processing depend critically on whether physical beneficiation can do the heavy lifting before any chemistry is introduced, a design principle that separates the more capital-efficient projects from their hard-rock counterparts.

Scale is the other headline. Critica reports an inferred mineral resource of approximately 1.8 billion tonnes at around 1,700 parts per million total rare earth oxides (TREO), a measure of how concentrated the rare earths are within the ore. The company characterises it as Australia’s largest clay-hosted rare earth oxide resource, a claim no cited third party has independently verified.

The project sits near Mount Magnet in Western Australia. Understanding that Jupiter is clay-hosted, rather than treating it as simply a big deposit, is what makes the processing strategy in the next section legible. The flowsheet is shaped by the geology, not by engineering preference.

The processing logic that could change the economics: mass rejection before leaching

The economic argument for Jupiter lives in a single idea: throw away most of the rock before you spend money on chemicals. In clay-hosted systems, the rare earths tend to concentrate in particular size fractions, which means physical separation can discard the barren bulk while keeping the valuable fraction.

The sequence is physical, not chemical. Screening, hydrocyclones, attritioning, and desliming work together to strip out gangue (the worthless material) before anything enters the leach circuit. Nothing corrosive gets added until the feed has already been slimmed down.

Testwork reported in May 2026 showed what that looks like in practice. Critica rejected approximately 95% of the original feed mass, lifting the concentrate to around 14 times the original ore grade while retaining roughly 81% of the magnet rare earths. Separate optimisation work then cut sulfuric acid consumption by around 30% against a prior reference baseline.

Follow the cost logic and each figure earns its place.

Acid consumption is a useful proxy for operating cost because reagents are typically a dominant line item in rare earth processing. Cut the feed by 90-95% and acid use falls with it, along with water, neutralisation capacity, and the volume of acidic tailings you have to manage afterward.

Rare earth processing economics are heavily influenced by reagent costs, particularly acid consumption, which is why the 30% reduction in sulfuric acid use reported in the May 2026 testwork carries more weight than a surface reading of the percentage might suggest.

The single lever that shrinks every downstream cost is mass rejection at the front end. Get rid of the waste cheaply, and the expensive part of the plant only has to handle a fraction of the tonnage.

This is not a Critica-specific insight. Engineering groups including Sedgman, Ausenco, and GR Engineering consistently point to mass rejection and flowsheet simplification as key de-risking steps in early studies, precisely because they tighten cost estimates and reduce the gap between Scoping-level and Feasibility-level economics.

The 95% mass rejection figure is the clearest explanation for why clay-hosted projects can plausibly target lower capital costs than hard-rock peers at equivalent output. It tells you the processing pathway is behaving the way its designers hoped, which is where project economics are ultimately won or lost.

From 84% to 98.2%: reading the purity progression and what it still needs to prove

The purity story is best read as a sequence, because each step represents a jump in process maturity rather than just a bigger number.

1. October 2025: approximately 84% TREO product purity, the first reported result and a proof that the flowsheet could produce a saleable oxide at all.
2. May 2026: approximately 97% TREO, a significant tightening that moved the product toward commercial specification territory.
3. 23 September 2026: 98.2% TREO, the most recent and highest result, approaching the kind of purity magnet-grade customers scrutinise.

Latest result: 98.2% TREO purity Reported 23 September 2026, the highest product purity achieved to date at Jupiter.

There is a detail in the testwork that matters more than the headline figure. Rare earth carbonate at approximately 58% TREO was produced at two independent laboratories, ANSTO and AMML, with comparable results from both. That dual-lab corroboration is the most technically meaningful part of the story, because it addresses whether the process is repeatable rather than a one-off.

Physical samples of oxide and iron byproduct material have also gone out to prospective customers for specification testing, the standard pre-commercial step before any offtake conversation gets serious. Separately, gallium and iron have been flagged as potential byproduct opportunities, though no value has been assigned and recovery methods are not yet determined.

What bench-scale purity does not yet tell you

Here is the pivot the number demands. Reproducibility across two labs is not the same thing as reproducibility across plant scales.

Laboratory testwork tends to use high-grade samples, controlled conditions, and short campaigns. Achieving 98.2% TREO on a bench does not guarantee the same purity, recovery, or reagent efficiency in a continuous pilot or a full-scale plant.

Bodies including the International Energy Agency, the USGS, and Geoscience Australia caution that scale-up frequently exposes new problems: impurity deportment shifting in unexpected ways, equipment fouling, and feed variability that a short bench campaign never reveals. Any of these can erode margins or force a flowsheet redesign.

None of this diminishes the progression. The point is calibration, not alarm. The purity trajectory is the clearest available signal of technical momentum at Jupiter, and reading it alongside the scale-up caveat gives you an accurate picture rather than an uncritical one.

What to watch next, and the risks that sit alongside the optimism

The temptation with a project like Jupiter is to treat the Scoping Study as a finish line. It is closer to a starting gun. Knowing which milestones carry genuine informational weight lets you interpret future announcements rather than react to headline numbers in isolation.

The proximate milestone is the Sedgman-led Scoping Study, targeted for Q3 2026 completion and supported by Snowden Optiro and SRK Consulting. It is worth being precise about what it delivers: concept-level capital and operating cost ranges and indicative economics, not the audited resource, detailed engineering, or pilot data that lenders require. The timeline has already slipped once, from initial first-half 2026 guidance.

Here is the fuller watchlist, in rough development sequence.

• Scoping Study release: concept-level economics with wide error bands, the first real look at whether the numbers hang together.
• Resource update: led by SRK Consulting, drawing on 145 infill drill holes completed in the priority zone, aimed at lifting confidence in the resource.
• Juno prospect results: the adjacent prospect has returned shallow rare earth intercepts with mineralogy comparable to Jupiter, hinting at resource extension.
• Pilot program: the multi-month campaign that tests whether bench-scale purity survives continuous operation.
• Offtake progress: customer sample testing is underway, but no binding agreements exist.

The appointment of Mike Keevan as Interim Studies Director in August 2026 signals intent to push the project from Scoping toward more advanced study phases. That is a structural step, not a result.

Risks that sit alongside the optimism

The single most important flag in the research package is financial. Critica reported cash of approximately $5.3 million at the end of June 2026, following an $8 million raise that began in November 2025. Its annual report carries a going-concern disclosure, noting material uncertainty regarding the company’s ability to continue as a going concern.

That disclosure sits alongside the technical progress rather than being cancelled out by it. It tells you the project’s advancement depends on further capital, which exposes equity holders to dilution and the risk of delay if market conditions tighten. No disclosures on the post-June financing position have surfaced publicly, an information gap worth holding in mind.

Offtake is the second risk. Magnet manufacturers demand demonstrated consistency before committing, as Adamas Intelligence and Benchmark Mineral Intelligence have noted, and no named partners have been publicly identified.

Then there is ESG and regulatory exposure. Rare earth processing generates chemical residues and can involve low-level radioactivity, and Western Australian approvals demand robust tailings management and closure planning. Analysts at CRU and Wood Mackenzie caution that until clay-hosted projects reach production and prove stable costs, risk perceptions and discount rates will stay elevated.

Mining environmental approvals in Western Australia involve multi-agency review of tailings management, water use, and radiological risk, all of which are materially more complex for rare earth processing operations than for base metal mines given the chemical residues and low-level radioactivity the flowsheet can generate.

Where Jupiter fits in Australia’s rare earth ambitions, and what the Scoping Study will actually settle

Jupiter is one piece of a national supply-chain picture that is filling out stage by stage. Lynas Rare Earths is in production from Mt Weld. Arafura Rare Earths’ Nolans project has moved through front-end engineering with strong government support. Iluka Resources is building its Eneabba refinery to process stockpiled concentrates, and Hastings Technology Metals’ Yangibana project is advancing through study stages. Jupiter sits earlier in that pipeline, at Scoping Study stage.

Rare earth supply chain risks amplify the strategic value of projects like Jupiter: when production remains concentrated in a small number of jurisdictions, any new source of consistent, high-purity oxide output carries geopolitical significance well beyond its tonnage.

What makes it strategically interesting is the deposit class. Geoscience Australia frames clay-hosted projects as a newer category that could broaden the country’s resource base beyond the hard-rock monazite and carbonatite systems that have dominated to date. That diversification carries weight given Australian critical minerals strategies list rare earths as strategic commodities, and given partners including Japan, the EU, the United States, and South Korea are actively engaging with Australian projects.

The strategic case, though, only converts to value if the economics hold. This is where being clear about the Scoping Study matters.

A Scoping Study sets the economic baseline. The Pre-Feasibility and Definitive Feasibility Studies, plus the pilot program, are where the real commercial questions get answered.

A Scoping Study delivers concept-level capital and operating cost ranges, indicative NPV and IRR, and a map of what the next study phase needs to investigate. What it does not deliver is the audited resource model, detailed engineering, and multi-month pilot data that banks require before they will lend. The numbers it produces carry wide error bands that only tighten through subsequent feasibility work.

Read that way, the Scoping Study is the beginning of Jupiter’s economic conversation, not its conclusion. The development pathway runs from Scoping Study, to resource update, to PFS or DFS, to pilot, to financing, to construction, with offtake needing to progress in parallel.

That framing is what lets you assess future Jupiter announcements with the right context, rather than comparing Scoping-level outputs against the PFS-level figures of more advanced projects. The technical momentum is real. Whether it becomes a mine depends on the harder, slower work that comes after Q3 2026.

This article is for informational purposes only and should not be considered financial advice. Investors should conduct their own research and consult with financial professionals before making investment decisions.

Past performance does not guarantee future results. Financial projections are subject to market conditions and various risk factors. Forward-looking statements regarding study timelines, purity outcomes, and development milestones are speculative and subject to change based on market developments and company performance.