Premier1 Lithium Uncovers New VMS Corridor at Carlisle and Mt Kersey System

Premier1 Lithium Uncovers a New VMS Corridor at Carlisle and Confirms a Large Hydrothermal System at Mt Kersey

Premier1 Lithium Limited (ASX: PLC) has released drilling results from its Yalgoo Gold Project in Western Australia that materially change the geological understanding of the project area. The headline finding is the identification of a previously unrecognised Volcanogenic Massive Sulphide (VMS) corridor at the Carlisle prospect, where high-grade gold mineralisation has been intercepted outside the existing Wadgingarra Inferred Mineral Resource boundary.

Simultaneously, a large hydrothermal system has been confirmed at the Mt Kersey prospect, with geochemical data pointing toward continued exploration upside to the south. The Premier1 Lithium new VMS corridor at Carlisle and hydrothermal system at Mt Kersey represent a fundamental shift in how management interprets the mineralising systems underpinning the Yalgoo project.

The 2026 reverse circulation (RC) drilling programme comprised 16 holes for a total of 2,776 metres across four prospects — Carlisle, Mt Kersey, Central Block, and Crescent South — and delivered a step-change in geological understanding.

Carlisle Emerges as the Standout: High-Grade Gold and a New VMS Signature

The Carlisle prospect has quickly become the most compelling target at the Yalgoo project, following results from both the 2025 and 2026 drilling programmes. Three RC holes — 26GGRC010, 26GGRC011, and 26GGRC012 — were designed to test down-dip and along-strike extensions of previously identified mineralisation at the western edge of the Wadgingarra resource area.

Two of the three holes returned coherent gold mineralisation along a NNW trend, with approximately 100 metres of strike currently defined and the system remaining open in both directions.

Key Carlisle Drill Intercepts

These intercepts sit outside the outline of the existing Wadgingarra Inferred Mineral Resource — currently estimated at 150,000 tonnes at 2.7 g/t Au for 13,000 ounces of contained gold — signalling potential for meaningful resource expansion.

Why the Geochemical Fingerprint Matters

What makes the Carlisle results particularly significant is not just the gold grades but the geochemical fingerprint accompanying them. Analysis of multi-element data from the 2025 and 2026 drilling has revealed a strong VMS pathfinder signature in both alteration minerals (actinolite-ankerite) and trace element geochemistry (Bi-Ba-Te-K-Sn-As-Cu-W-Sb-Ag).

This signature had not been recognised in prior work at Carlisle and introduces an entirely new exploration framework for the area.

Executive Director Simon Phillips commented: "The recent drilling programme has highlighted the significant exploration potential across the Yalgoo project, in particular the identification of a VMS association at Carlisle and the nearby Olive Queen Prospects, which opens up a huge opportunity for the Company to expand the Wadgingarra Resource with relatively simple and cost-effective exploration."

The mineralisation at Carlisle is hosted in high-magnesium basalts — a rock type commonly associated with VMS systems — and sits open to the south and approximately 150 metres to the north, where historical drilling at the Cumberland Prospect returned grades up to 40 g/t Au.

Furthermore, a similar VMS alteration signature has been identified in 2025 drill hole 25GGRC023 at the Olive Queen West prospect. This raises the possibility that the Olive Queen–Cumberland–Carlisle trend represents a previously unrecognised VMS corridor extending over a meaningful strike length.

Understanding VMS Mineralisation: Why This Discovery Framework Matters

What Is a VMS System?

VMS (Volcanogenic Massive Sulphide) deposits form on or near the seafloor when metal-rich hydrothermal fluids vent through volcanic rocks and precipitate sulphide minerals. They are among the most economically significant deposit types in the world, capable of hosting not only gold but also copper, zinc, lead, and silver in concentrations that support large-scale mining operations.

Why Does the VMS Signature Matter at Carlisle?

VMS systems typically occur in clusters along predictable geological corridors, meaning the identification of one mineralised zone often signals the presence of additional targets nearby. Historical drilling across the Wadgingarra area was largely restricted to gold-only assays, meaning the multi-element pathfinder data now being generated by Premier1 provides a fundamentally new lens through which to evaluate existing and prospective mineralisation.

Glossary of Key Terms

Mt Kersey: A Large Hydrothermal System With Continued Exploration Potential

Nine holes were drilled at Mt Kersey over a 550-metre strike extent, targeting a 300m x 200m gold-in-soil anomaly with peak values up to 88 parts per billion (ppb) and a coincident large-scale pathfinder anomaly (Te, Bi, As, Cu, Mo, Zn) extending across 1 kilometre of strike.

While gold grades at Mt Kersey were lower than anticipated, the drilling successfully confirmed the presence of a large magmatic hydrothermal system, with gold and pathfinder element anomalism intersected across multiple holes.

Key Mt Kersey Drill Intercepts

An important observation from the southern portion of the Mt Kersey drilling area is the development of sericite/biotite alteration and increasing molybdenum and arsenic pathfinder anomalism in holes 26GGRC001, 26GGRC002, and 26GGRC003. This signature suggests a possible orogenic overprint, providing additional prospectivity to the south.

Critically, historical drilling to the south of the 2026 programme is now interpreted to have been positioned too far to the west to have adequately tested the prospective structural trend, leaving the southern extension of the Mt Kersey system effectively untested by well-positioned holes.

Exploration Manager Paul Smith commented: "At Mt Kersey we have confirmed a large hydrothermal system; while the drilling returned only low-grade gold, the geochemistry points to remaining prospectivity to the south and we will continue to assess that opportunity."

Other Prospects: Central Block and Crescent South

Drilling at the Central Block tested two electromagnetic anomalies from a 2022 geophysical survey and an area of historical gold workings. Massive to semi-massive sulphides were intersected in two of the three holes drilled (26GGRC013 and 26GGRC014); however, no economic gold or base metal mineralisation was returned.

At Crescent South, a single hole (26GGRC016) tested the up-dip position of a high-grade gold intersection from 2025 (25GGRC001: 3m @ 31.5 g/t Au, including 1m @ 91.9 g/t Au from 97m). No significant gold mineralisation was returned in this follow-up hole.

A Clear and Structured Path Forward

The 2026 RC programme has generated a well-defined exploration roadmap across the Yalgoo project. The Premier1 Lithium new VMS corridor at Carlisle and hydrothermal system at Mt Kersey will guide the company's immediate exploration strategy, with prioritised next steps as follows:

1. Carlisle — Ground EM/IP Geophysics: Geophysical surveys will identify the core of the interpreted VMS system, including potential massive sulphide lenses invisible to conventional surface sampling.
2. Carlisle — Follow-Up RC Drilling: Drill traverses along strike to the north (toward Cumberland) and to the south, testing the full extent of the interpreted VMS corridor.
3. Mt Kersey — Detailed Geochemical Assessment: Continued analysis of multi-element and alteration datasets to refine targeting to the south.
4. Wadgingarra Mineral Resource — Integration and Expansion Evaluation: Carlisle results will be integrated into the existing resource model to evaluate expansion potential beyond the current 150,000t at 2.7 g/t Au for 13,000 oz Inferred Resource.

The Yalgoo Gold Project: Strategic Context and Location

Premier1 holds a 100% interest in 266 km² of gold-mineralised tenements within the Yalgoo–Singleton Greenstone Belt, one of Western Australia's historically significant gold-producing regions. The acquisition of 100% of the Yalgoo Gold Project was completed in January 2026.

The project is strategically located between two established gold producers — Ramelius Resources and Capricorn Metals — and sits within a district that has attracted renewed attention following the announced merger between Regis Resources and Vault Minerals.

In addition, the nearby Golden Grove zinc-copper-gold system represents one of the most significant Archaean VMS deposits in Australia, providing strong geological precedent for the VMS corridor interpretation now being advanced at Carlisle.

Why Investors Should Keep a Close Eye on Premier1 Lithium

Several factors combine to make this a notable exploration development worth monitoring:

• Resource expansion potential: High-grade gold at Carlisle has been confirmed outside the existing Wadgingarra boundary, with the system open in both directions. Integration of these results could support expansion of the current 13,000 oz at 2.7 g/t Au resource.
• A new discovery framework: The VMS affinity identified at Carlisle — supported by alteration mineralogy and a distinctive multi-element pathfinder signature — has reframed exploration across the entire Yalgoo project.
• Cost-effective follow-up programme: Management has outlined a capital-efficient next-stage programme anchored by ground geophysics and targeted RC drilling.
• District-scale location: The Yalgoo–Singleton Greenstone Belt is increasingly active, with major producers operating in the surrounding region.
• Strong geological team: The programme was compiled by Exploration Manager Paul Smith (AIG member) and reported in compliance with the 2012 JORC Code, providing confidence in data quality and reporting standards.

The Premier1 Lithium new VMS corridor at Carlisle and hydrothermal system at Mt Kersey discoveries have fundamentally altered the geological understanding of the Yalgoo project, creating multiple pathways for value creation through systematic exploration.

Key Takeaway: Premier1 Lithium has delivered a genuine exploration step-change at its Yalgoo Gold Project, with the identification of a new VMS corridor at Carlisle opening up a previously unrecognised discovery pathway. With geophysics and follow-up drilling planned to test a multi-prospect trend that is open in both directions, and continued assessment of the Mt Kersey hydrothermal system underway, the company has a well-structured and catalyst-rich programme ahead. Investors with an interest in early-stage gold exploration in Western Australia's proven greenstone belts should keep a close watch on upcoming results.

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