Rimfire Pacific Pulls 22.7% Scandium From Murga Rock Using Cheaper Leaching Route
Key Takeaways
- Stage 2 bottle roll tests at Murga recovered 22.7% of scandium from saprolite and 15.2% from laterite at 15 weeks, with tests still running.
- Rimfire projects at least 60% (saprolite) and 30% (laterite) recovery over 52 weeks, but that is a linear extrapolation, not a measured result.
- Murga's host rocks average about 16% Fe versus 34% Fe at Rio Tinto's Burra deposit, the core of the lower-capital atmospheric leaching thesis.
- The saprolite leach solution showed a scandium to iron ratio of 2.24 mg Sc/g Fe, with low acid use of 0.34t/t, supporting easier downstream purification.
- Column leach, agitated tank leach and bottle roll updates are due between early November and early December 2026, feeding a desktop financial study; the data so far comes from just two samples from one drillhole.
Scandium recoveries of 23% and 15% at 15 weeks support lower-capital pathway at Murga
Scandium is being pulled out of low-iron rock at atmospheric pressure, and the early numbers are better than a quick glance suggests. Rimfire Pacific Mining (ASX: RIM) reported that Stage 2 bottle roll tests on material from the Murga Scandium Deposit (11.9Kt Sc Oxide, per the 13 April 2026 resource announcement) reached scandium recoveries of 22.7% from saprolite and 15.2% from laterite at 15 weeks. The tests are continuing.
A projection sits alongside those results. If the linear line of best fit rate holds, recoveries of at least 60% (saprolite) and 30% (laterite) could potentially be achieved over 52 weeks. That is a projection, not a measured result.
The update follows the 14-day bottle roll tests announced on 23 June 2026. Atmospheric leaching could be simpler and lower-capital than the High Pressure Acid Leaching (HPAL) route that other Fifield deposits are contemplating.
Bronwyn Barnes, Executive Chair
“The deposit’s low-iron host rocks represent a potential gamechanger when compared to the other deposits in the area…”
Barnes also described the recoveries at the end of 15 weeks as “highly encouraging”.
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How the Stage 2 bottle roll tests are tracking
15-week results and 52-week projection
Two samples are under test, both composite HQ quarter core samples from diamond drillhole FI2679. Each is leached at atmospheric pressure and ambient temperature.
| Host rock | Sample size | 15-week recovery | 52-week projection |
|---|---|---|---|
| Saprolite | **0.74 kg** | **22.7%** | At least **60%** |
| Laterite | **1 kg** | **15.2%** | At least **30%** |
The projections come from a linear line of best fit (excluding the initial rapid extraction) applied to weekly recovery data and extrapolated over 52 weeks. In plain terms, it assumes the leaching keeps going at the same steady pace.
Rimfire justifies the longer timeframe because heap leaching of analogous laterite nickel cobalt scandium deposits typically takes place over 100 to 400 days (14 to 57 weeks), or even longer. Published research papers also confirm that European and West Australian saprolite ores achieve 70 to 80% extractions over extended leaching periods.
Other observations at 15 weeks
- Acid use: Sulphuric acid consumption was 0.34t/t (saprolite) and 0.23t/t (laterite), which the company considers low for atmospheric leaching.
- Scandium to iron ratio: The saprolite pregnant leach solution (the liquid carrying the dissolved metals) showed a high ratio of 2.24 mg Sc/g Fe relative to atmospheric leaching of other scandium ores. Less iron relative to scandium makes downstream separation easier and supports higher purity final products.
- Laterite recoveries: These are lower than saprolite, which may be attributable to calcium, manganese and magnesium consuming more acid, leaving less for scandium extraction. This is a possible explanation, not a confirmed one.
Why low-iron scandium matters: atmospheric leaching explained
Atmospheric leaching dissolves metal from crushed rock using acid at ambient temperature and normal pressure. HPAL uses high pressure, which the company describes as more capital intensive and complex.
Iron matters because it is a contaminant. According to the announcement, when iron is excessively high relative to scandium it swamps extraction sites, resin beds or organic phases, making scandium hard and costly to purify. A higher scandium to iron ratio reduces the number of complex iron-stripping and scrubbing stages needed.
Murga’s host rocks average approximately 16% Fe (22.8% Fe2O3). Rio Tinto’s Burra Scandium Deposit has a combined Mineral Resource Estimate iron grade of 34% Fe (48.7% Fe2O3). For you as an investor, that gap is the core of the Murga thesis: Rimfire says its potential value lies in the possibility that its scandium can be viably extracted using less complex, less capital-intensive technology.
Other Fifield deposits are contemplating HPAL, including Syerston (Sunrise Energy Metals), Burra and Flemington. Murga sits adjacent to Syerston in the Fifield District, approximately 70 km NW of Parkes in central NSW.
Two types of scandium mineralisation are emerging:
- A near-surface laterite / saprolite-hosted clay dominant type, with grades ranging up to 320ppm Sc (491 ppm Sc Oxide).
- An underlying lower saprolite / saprock-hosted type, with grades ranging up to 120 ppm Sc (184 ppm Sc Oxide).
Barnes pointed to the demand picture:
Bronwyn Barnes, Executive Chair
“Globally, scandium is becoming a very high-value emerging critical mineral of growing strategic importance, with demand accelerating across advanced manufacturing, AI data centre, defence, and aerospace industries.”
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Next steps: three work streams feed a desktop financial study
Rimfire has expanded its metallurgical study to three work streams, guided by Boyd Willis, the company’s Metallurgical Process Consultant, who has over 40 years of process engineering experience:
- Stage 2 (long term) bottle roll leaching test work.
- Column leach test work.
- Agitated tank leach test work.
Rimfire aims to deliver updates on the following timeline:
- Column leach update by early November 2026.
- Agitated tank leach update by late November 2026.
- Bottle roll update in early December 2026.
All the data is intended to underpin a desktop financial study, the Murga Scandium Metallurgical Study, to determine the viability of using atmospheric leaching at Murga. Those three updates are the near-term milestones to watch.
The Fifield Project is subject to an Earn In Agreement with Golden Plains Resources (GPR), which can earn a 50.1% interest under the agreement’s conditions.
Keep the sample base in perspective. The tests use only two samples from one drillhole (FI2679), and further bottle roll tests are being undertaken to verify the results. The announcement does not disclose capital cost figures or conclusions on commercial viability.
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