Greentech Metals’ High-Grade Platinum at Munni Munni

GreenTech Metals Limited (ASX: GRE) has released assay results from its Phase 1 drilling and resampling programme at the Munni Munni PGE-Cu-Ni Project in Western Australia’s West Pilbara region. The results deliver some of the highest individual platinum-palladium-gold grades recorded at the Ferguson Reef, opening the door to a substantially expanded mineral resource and confirming GreenTech Metals’ high-grade platinum discovery at Munni Munni.

The programme, completed in March 2026, combined new reverse circulation (RC) and diamond drilling with systematic resampling of on-site preserved historical core. This three-pronged approach has simultaneously validated decades of prior exploration data and uncovered mineralisation styles not previously captured in the project’s resource model.

“We believe that our approach of focusing on broader zones of mineralisation and the large-scale exploration opportunity across the 225km² intrusive will continue to unlock this world class exploration opportunity,” said James Rattenbury, Chief Executive Officer, GreenTech Metals Limited.

A Programme Designed to Do More Than Drill

The Phase 1 programme was originally planned as a straightforward quality assurance exercise. The company intended to drill up to 20 RC and diamond holes for approximately 6,000 metres to verify historical data ahead of a JORC (2012) resource re-estimation. What emerged was considerably more significant.

Following an assessment of historical core stored in on-site sheds and a core farm at Munni Munni, GreenTech modified the scope to incorporate systematic resampling of that preserved material. The final programme comprised three distinct workstreams:

• 6 twin holes — drilled to directly validate historical assay data, confirming the integrity of prior drilling campaigns spanning from 1985 to 2002.
• 6 infill RC holes — drilled in new areas to test reef continuity and identify grade extensions.
• 16 historical holes resampled — selected for broad spatial coverage across the Ferguson Reef, spanning its full depth range.

Total drilling completed across the new programme reached 2,928.7 metres.

The Numbers That Matter: Standout Intercepts

Every single drill hole in the programme returned significant mineralised intercepts. This result materially strengthens confidence in the Ferguson Reef’s grade continuity and structural consistency.

New RC and Diamond Drilling Results

Drill Hole	Interval (m)	PGE3 (g/t)	Cu (%)	Ni (%)	From (m)
26GTRC010	12	3.13	0.30	0.17	90
Including	2	8.37	0.63	0.34	98
26GTRC011	11	1.15	0.15	0.11	116
Including	2	2.96	0.34	0.18	117
26GTRC007	15	1.70	—	—	24
And	3	—	0.34	0.16	22
26GTRC006	6	2.26	—	—	173
And	2	1.75	—	—	183

PGE3 = Pt + Pd + Au

The standout result is hole 26GTRC010, which returned 2m at 8.37 g/t PGE3, 0.63% Cu and 0.34% Ni from 98m. This represents one of the highest individual metal grades recorded at the Ferguson Reef, reinforcing the significance of GreenTech Metals’ high-grade platinum discovery at Munni Munni.

Twin Hole Validation Results

Drill Hole	Interval (m)	PGE3 (g/t)	Cu (%)	Ni (%)	From (m)
26GTDD004	11	1.88	0.14	0.09	526
Including	1	4.43	0.46	0.21	535
26GTDD002	4	2.29	0.29	0.16	244
26GTRCD003	6	1.57	—	—	324
And	7	—	0.40	0.15	322
26GTDD001	12	1.08	—	—	186
Including	2	2.27	—	—	186

Selected Historical Core Resampling Highlights

Historic Hole	Interval (m)	PGE3 (g/t)	Cu (%)	Ni (%)	From (m)
MMD117	2	5.90	0.19	0.14	107
MMD115	4.5	2.67	—	—	50.75
MMD045	2	2.64	0.25	0.11	137.5
MMD084	11.25	1.49	—	—	754.75
MMD099	22	0.89	—	—	770

The resampling of historical hole MMD117 is particularly notable. The 2m intercept grading 5.90 g/t PGE3 from 107m demonstrates the presence of very high-grade zones within the existing resource footprint that were defined under the older JORC (2004) framework.

Understanding PGE3 and Why It Matters to Investors

What Is PGE3?

PGE3 refers to the combined grade of three precious metals: Platinum (Pt), Palladium (Pd), and Gold (Au). This is the key grade metric used in this programme to characterise platinum group element mineralisation at the Ferguson Reef.

At Munni Munni, the historical resource was modelled using PGE4, which adds Rhodium (Rh) to the suite. Rhodium is one of the world’s rarest and most valuable metals. GreenTech’s upcoming JORC (2012) resource re-estimation will use a PGE4 plus Au framework and will also incorporate a Net Smelter Return (NSR) cut-off that accounts for payable copper and nickel alongside the PGE suite.

Why Does This Matter?

The historic resource was calculated using a 1.9 g/t PGE cut-off, which excluded significant copper and nickel mineralisation occurring outside the reef’s high-grade core. The new programme has shown that Cu-Ni sulphide intervals exist both above and below the PGE reef horizon.

These intervals were essentially invisible to the old resource model. By incorporating these metals into the resource envelope via an NSR cut-off, the re-estimated resource could capture considerably more value per tonne than the historical figure suggests.

Key Terms Explained

• PGE (Platinum Group Elements): A family of six rare metals including platinum, palladium, rhodium, ruthenium, iridium, and osmium, used in catalytic converters, electronics, and fuel cells.
• Ferguson Reef: The principal mineralised zone at Munni Munni, hosted at the contact between gabbroic and ultramafic rock sequences.
• NSR (Net Smelter Return): A cut-off methodology that accounts for the combined economic value of all payable metals, rather than a single metal grade threshold.
• JORC Code (2012): The Australasian standard for reporting mineral exploration results and resource estimates, requiring rigorous quality control validation.
• RC (Reverse Circulation): A drilling method that returns rock chips to surface through the drill string, commonly used for cost-effective infill and exploration drilling.
• DD (Diamond Drilling): A drilling method that recovers intact cylindrical core samples, providing high-quality geological and grade data.
• Twin Hole: A new drill hole deliberately located close to an existing historical hole to directly compare results and validate historical assay data.

Three Key Discoveries From the Phase 1 Programme

The results point to three structural shifts in how GreenTech and the market should view Munni Munni’s potential.

High-Grade PGE Zones Are Thicker and More Widespread Than Previously Known

Multiple intersections across the Ferguson Reef have returned grades at or above 8.8 g/t PGE3, among the highest individual metal grades seen at the project. The distribution of high-grade intercepts across multiple cross-sections suggests these zones are not isolated anomalies, but systematic features of the reef architecture.

Furthermore, this validates GreenTech Metals’ high-grade platinum discovery at Munni Munni and indicates strong potential for resource expansion. The reef’s consistency across depth and strike is a particularly encouraging finding.

Copper and Nickel Have Been Systematically Under-Counted

The historic resource model only included Cu-Ni mineralisation within zones defined by a 1.9 g/t PGE cut-off. Both new and historical resampling results demonstrate that copper and nickel sulphide mineralisation extends significantly outside these boundaries, particularly in shallow eastern zones.

This mineralisation was largely unassayed in prior programmes, meaning the historical resource underrepresents the project’s full metal endowment. In addition, these extensions could meaningfully widen the economic resource envelope under the new NSR-based approach.

Shallow Eastern Zones May Suit Open-Cut Mining

Results from the eastern portions of the Ferguson Reef highlight significant shallow, thicker Cu-Ni sulphide zones with a shallow plunge from surface. GreenTech has flagged that this geometry could be amenable to bulk open-cut mining — a materially different and potentially lower-cost extraction pathway than the underground scenario implied by the historical resource model.

Historical Resource Context

The existing historical resource at Munni Munni provides an important reference point. The scale of what GreenTech is working with is considerable.

Munni Munni Historical Mineral Resource Estimate (JORC 2004)

Category	Mt	Pt (g/t)	Pd (g/t)	Au (g/t)	Rh (g/t)	Cu (%)	Ni (%)
Measured	12.4	1.1	1.4	0.2	0.1	0.09	0.07
Indicated	9.8	1.1	1.6	0.3	0.1	0.22	0.11
Inferred	1.4	1.1	1.6	0.3	0.1	0.15	0.09
Total	23.6	1.1	1.5	0.2	0.1	0.15	0.09

Important note: This is a historical estimate only, not reported in accordance with JORC Code (2012). A competent person has not done sufficient work to classify these estimates as mineral resources under JORC (2012). GreenTech is in the process of independently validating prior data to enable re-estimation under the current code.

The historical resource was defined across 328 drill holes totalling 91,077m over the period 1985–2002. This represents a substantial body of prior work that GreenTech’s twin hole and resampling programme has now systematically begun to validate.

Pathway to a JORC (2012) Resource: What Comes Next?

GreenTech has engaged Snowden Optiro, a specialist resource consultancy, to lead the quality control validation and re-estimation process. The key milestones ahead are clearly defined:

• All assay data from the Phase 1 programme merged into the project database
• Updated metallurgical test work underway to inform NSR modelling
• JORC (2012) Mineral Resource Estimate targeted for June 2026

The re-estimated resource is expected to use PGE4 (Pt + Pd + Rh) + Au as the primary grade basis, combined with an NSR cut-off to capture payable copper and nickel, underpinned by the validated historical dataset.

The shift from the historic 1.9 g/t PGE cut-off to an NSR-based approach could meaningfully widen the economic mineralisation envelope, potentially increasing both resource tonnes and contained metal value relative to the 2002 estimate.

Investment Thesis: Why Munni Munni Deserves Attention Now

The Phase 1 results collectively reframe the Munni Munni opportunity in several important ways.

Grade quality is confirmed. Every new hole intersected significant mineralisation, and the highest grades in the programme rival and in some cases exceed the best historical results. This removes a material uncertainty about reef continuity.

The resource is likely to grow. By incorporating Cu-Ni mineralisation that the historical model excluded, and by expanding the grade envelope through an NSR cut-off, the JORC (2012) re-estimation has a sound basis to potentially reflect greater value than the historical 23.6 Mt at 2.9 g/t 4E estimate.

A new mining scenario may be emerging. The identification of shallow, bulk-mineable Cu-Ni zones in the eastern portions of the reef represents a potentially significant addition to the project’s optionality. This was not part of the historical development narrative.

Historical data is validated. The success of twin hole drilling in replicating historical results means the 91,077m of prior drilling that underpins the existing resource is a credible foundation, not a liability.

Scale of the landholding. GreenTech holds a dominant 500km²+ tenement position across the West Pilbara, with Munni Munni sitting on a 225km² layered intrusion. However, the vast majority of this area remains underexplored, representing considerable long-term upside.

Key Project Metric	Detail
Historical Resource	23.6 Mt @ 2.9 g/t 4E (PGE+Au) for 2.2 Moz
Ferguson Reef Strike	Laterally continuous across multiple kilometres
Intrusive Scale	225 km²
Total GRE Tenement Holding	>500 km²
New Holes Drilled (Phase 1)	12 (6 twin + 6 infill)
Historical Holes Resampled	16
Total Phase 1 Metres	2,928.7m
JORC (2012) MRE Target	June 2026

Why Investors Should Watch GRE Closely

The June 2026 resource re-estimation represents an immediate and well-defined catalyst. If Snowden Optiro’s quality control validation supports conversion of the historical estimate — and the new drilling data suggests it will — GreenTech will have a fully JORC (2012) compliant resource for the first time in the project’s history.

That milestone transforms Munni Munni from a historically documented deposit into a reportable, investable asset that can be benchmarked and valued by the market on a consistent basis.

Beyond that immediate catalyst, the emergence of shallow Cu-Ni zones with potential open-cut applicability adds a layer of optionality that broadens the project’s development pathway. This broadens its relevance to investors across both the PGE and base metals space.

The combination of validated high-grade zones, expanded mineralisation understanding, and potential for alternative mining scenarios positions GreenTech Metals’ high-grade platinum discovery at Munni Munni as a compelling exploration story with multiple pathways to value creation.

Key Takeaway: The Phase 1 programme has demonstrated that Munni Munni hosts high-grade, laterally continuous PGE-Cu-Ni mineralisation with greater depth and grade extent than the historic resource captured. The JORC (2012) re-estimation due in June 2026 now represents a clear and near-term value catalyst for investors following ASX: GRE.

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