Heavy Rare EARTHS Ltd
- ASX Code: HRE
- Market Cap: $6,657,084
- Shares On Issue (SOI): 208,033,882
Heavy Rare Earths Uncovers High-Grade HREO Domains at Subron Project
Heavy Rare Earths (ASX: HRE) has released an updated strategic review of its Subron Rare Earths Project in Western Australia, delivering expanded drilling data, individual lanthanide assays and a complete drill collar table alongside its original 20 July 2026 announcement. These Heavy Rare Earths Subron rare earths project high grade HREO results provide investors with a substantially more detailed picture of the mineralisation identified beneath the project area.
The central finding from the review is that Subron may host a heavy rare earths deposit of meaningful scale, a distinction that carries considerable weight in the current critical minerals landscape given the relative scarcity of heavy rare earth supply globally.
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What the Strategic Review Found
The review was led by specialist consultant Claudio Sheriff, whose background includes rare earths discovery work at Voltaic Strategic Resources, Asra Minerals and Northern Minerals. Sheriff examined the company's full 547-hole aircore drill database, focusing specifically on the distribution of Heavy Rare Earth Oxides (HREO) and using regional magnetics and structural interpretation to constrain target areas.
Applying a cut-off of more than 1,000 parts per million (ppm) Total Rare Earth Oxides (TREO), the database returned 190 significant intercept drill intervals and 583 individual one-metre intervals grading above that threshold. According to the announcement, these intervals average 1,685 ppm TREO with 441 ppm HREO, representing a 25% HREO ratio.
Applying a more targeted cut-off of greater than 300 ppm HREO produced 150 significant intercept drill intervals and 454 individual one-metre intervals above that threshold, averaging 1,653 ppm TREO with 579 ppm HREO for a 38% HREO ratio.
For context, the existing JORC Mineral Resource at Subron stands at 159 million tonnes at 870 ppm TREO, as reported in October 2023. The high-grade HREO domains identified in the current review substantially exceed that resource-average grade, pointing to what management describes as a distinct and potentially higher-value subset within the broader mineralised system.
"The strategic review of Subron has been very rewarding, and the findings show it to be one of the highest HREO ratio residual clay deposits of its kind. This is supported by the drilling data showing 150 intersections grading above 300ppm HREO with an outstanding 441ppm HREO average grade and 38% HREO ratio. This has immense value and provides a clear point of difference from most rare earths projects," said Jason Barnett, Managing Director and CEO of Heavy Rare Earths.
Seawolf Prospect Delivers Standout Intercept
Among the ten high-grade HREO domains identified across the project, the newly named Seawolf Prospect has emerged as a priority target, hosting the highest-grade intersections recorded at Subron to date.
The standout result from Seawolf, reported from hole AC360, is 8 metres at 3,057 ppm TREO with a 1,344 ppm HREO average, representing a 42% HREO ratio, from 27 metres depth.
Breaking this intercept down into its individual two-metre intervals illustrates the consistency of the mineralisation:
| Interval | From (m) | To (m) | TREO (ppm) | HREO (ppm) | HREO Ratio |
|---|---|---|---|---|---|
| AC360 | 27 | 29 | 2,756 | 671 | 24% |
| AC360 | 29 | 31 | 3,608 | 1,393 | 39% |
| AC360 | 31 | 33 | 4,042 | 2,552 | 63% |
| AC360 | 33 | 35 | 1,820 | 759 | 42% |
The 31 to 33 metre interval is particularly notable, with a 63% HREO ratio and more than 2,552 ppm HREO, among the more compelling individual intervals disclosed in the entire dataset.
Additional intercepts from across the broader project further illustrate the quality of these HREO-enriched zones:
| Hole | From–To (m) | TREO (ppm) | HREO (ppm) | HREO Ratio |
|---|---|---|---|---|
| AC225 | 26–28 | 7,222 | 1,814 | 25% |
| AC225 | 24–26 | 6,211 | 1,437 | 23% |
| AC321 | 38–40 | 2,200 | 1,499 | 68% |
| AC321 | 40–41 | 2,337 | 1,447 | 62% |
| AC201 | 32–34 | 3,068 | 1,002 | 33% |
| AC200 | 22–24 | 2,317 | 1,525 | 66% |
| AC326 | 34–36 | 3,196 | 1,236 | 39% |
The peak HREO ratio recorded across the entire database reaches 70%, a figure management has flagged as a distinguishing feature relative to many rare earths projects globally.
Understanding Heavy Rare Earth Oxides
Why Does the HREO Classification Matter?
Rare earths comprise a group of 17 elements typically divided between light rare earth elements and heavy rare earth elements. The HREO group tracked at Subron includes Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium and Yttrium.
The commercial distinction matters because certain heavy rare earths, particularly Dysprosium and Terbium, are key inputs for the high-strength permanent magnets used in electric vehicle motors, wind turbines and defence applications. These elements are scarcer in nature than light rare earths, and the global supply chain for them remains relatively concentrated.
The HREO ratio, expressed as the proportion of HREO relative to TREO in a given sample, is a useful indicator of a deposit's relative value per tonne of ore. Many ionic clay rare earths deposits report HREO ratios in the single digits or low teens. A deposit consistently returning ratios in the 25% to 70% range sits in a fundamentally different category.
| Term | Definition |
|---|---|
| TREO | Total Rare Earth Oxides, the sum of all rare earth element oxides in a sample, measured in ppm |
| HREO | Heavy Rare Earth Oxides, the subset including Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y |
| MREO | Middle Rare Earth Oxides, a transitional grouping between light and heavy rare earths |
| HREO Ratio | The proportion of HREO expressed as a percentage of TREO |
| Ionic Clay / Residual Clay | A deposit style where rare earths are adsorbed onto clay minerals in weathered profiles, generally associated with lower-cost extraction methods |
| Significant Intercept | A drill interval meeting a defined minimum grade cut-off |
| JORC | The Australasian standard for public reporting of exploration results and mineral resources |
Structural Framework Across Ten Domains
A key contribution of the strategic review is the structural interpretation used to delineate the high-grade zones. Regional magnetics and structural analysis were applied to identify ten high-grade HREO domains, organised along structural corridors named Barents, Bering and Bismarck after submarine-prominent seas.
The combined strike length of these constrained high-grade domains is approximately 12.9 kilometres, sitting within the footprint of the existing JORC resource area, with additional targets identified outside that boundary.
The name Subron, short for Submarine Squadron, references the interpreted elongated, submarine-like geometry of the HREO-rich mineralisation lodes. The project was previously named Cowalinya.
Subron is located in south-central Western Australia, approximately 110 kilometres north-north-east of the port of Esperance and 350 kilometres south of the Kalgoorlie Rare Earth Processing Facility, a positioning management has described as logistically favourable.
"A cluster of HREO domains in a sea of regional prospectivity, emerging at Subron, are remarkable," said Claudio Sheriff, Rare Earths and Critical Minerals Consultant.
Work Program Ahead
What Are the Near-Term Priorities?
HRE has outlined a staged program intended to build on these early findings. Near-term priorities include:
- Completion of the full strategic review, with additional findings expected in coming weeks
- A maiden high-grade, high-HREO-ratio mineral resource estimate that re-domains the current JORC resource to isolate the higher-grade zones
- Mineralogy characterisation to identify REE-bearing mineral species within specific geological layers
- Metallurgical testwork targeting particular stratigraphic layers within the saprolite profile
- Resource infill drilling aimed at converting Inferred resources to the Indicated category
The company is furthermore investigating whether archived variability samples from existing aircore drilling can support metallurgical testwork, potentially avoiding the cost and time associated with re-drilling.
Preliminary data referenced in the announcement indicates that particle size analysis on mineralised saprolite at Subron shows 78.5% of REEs confined to the finer (-25 micron) size fraction. This fraction itself represents only 37.2% of the bulk saprolite feed mass but carries a REE grade 116% higher than the bulk feed.
Preliminary leach testwork has reportedly demonstrated up to 91% TREO recovery from Subron South using a 5% hydrochloric acid solution at 30 degrees Celsius, an early indicator of processing amenability that management notes will require further confirmation through additional testwork.
Investment Considerations
The following table summarises key parameters disclosed in the strategic review update:
| Factor | Detail |
|---|---|
| Existing JORC Resource | 159 Mt at 870 ppm TREO (announced October 2023) |
| High-Grade HREO Domain Strike | Approximately 12.9 km identified, within existing resource area |
| Peak HREO Ratio | Up to 70% |
| High-Grade HREO Intercept Set Average | 1,653 ppm TREO / 579 ppm HREO at 38% HREO ratio (>300 ppm HREO cut-off) |
| Deposit Style | Ionic / residual clay |
| Location | 110 km NNE of Esperance port; 350 km from Kalgoorlie REE processing infrastructure |
| Drilling Database | 547 aircore holes, wide-spaced at approximately 400m x 200m |
The wide drill spacing across the existing database, at roughly 400 metres by 200 metres, means many of the identified high-grade HREO zones have not yet been fully drilled out. This leaves considerable scope for further definition through infill drilling, according to the company.
The ionic clay deposit style is also considered relevant from a processing perspective. This style of mineralisation, where rare earths are adsorbed onto clay minerals within a weathered saprolite profile, has historically been associated with simpler extraction processes compared with hard-rock rare earth deposits. The preliminary leach testwork results are consistent with that characteristic, though further metallurgical work will be required to confirm commercial viability.
The REO distribution derived from the greater than 300 ppm HREO drilling dataset shows enrichment in Yttrium oxide, Dysprosium oxide and Terbium oxide, three elements considered significant within the HREO suite due to their application in high-strength permanent magnets.
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Outlook
What Is the Significance of the HREO Ratio at Subron Compared to Other Rare Earths Projects?
According to the company, an HREO ratio of 38% across the high-grade intercept dataset compares favourably with many rare earths deposits globally, which commonly report ratios in the single digits or low teens.
What Work Remains Before a Resource Estimate Can Be Finalised?
The company has indicated that re-domaining of the existing JORC resource, mineralogy characterisation, and metallurgical testwork are required before a maiden high-grade HREO resource estimate can be completed.
Does the Wide Drill Spacing Represent a Limitation on the Current Findings?
Management has characterised the approximately 400 metre by 200 metre drill spacing as an opportunity for further definition through infill drilling, rather than a constraint on the results reported to date.
The Heavy Rare Earths Subron rare earths project high grade HREO results have consequently repositioned Subron from a large but broadly characterised project toward one displaying a high-grade, high-HREO-ratio profile. With ten identified mineralised domains spanning approximately 12.9 kilometres of strike, 150 drill intercepts averaging 579 ppm HREO at a 38% ratio, and a best intercept of 8 metres at 3,057 ppm TREO and 1,344 ppm HREO at Seawolf, the review provides a dataset that investors may wish to monitor closely.
Upcoming newsflow, including finalisation of the strategic review, mineralogy results, metallurgical testwork outcomes and a maiden high-grade HREO resource estimate, represents a series of milestones that may sharpen the market's understanding of Subron's value over the coming months.
Want to Know More About Heavy Rare Earths and the Subron Project?
With ten high-grade HREO domains identified across 12.9 kilometres of strike, standout intercepts at the Seawolf Prospect, and a series of significant milestones on the horizon — including a maiden high-grade HREO resource estimate and metallurgical testwork results — Heavy Rare Earths (ASX: HRE) is shaping up as a project worth watching closely. Investors looking to stay across the latest developments at Subron, including upcoming announcements on mineralogy, infill drilling and resource re-domaining, can find full company and project details at the Heavy Rare Earths investor page.
