Tertiary Minerals plc (AIM: TYM), an AIM-traded mineral exploration company focused on energy transition metals, has announced the final laboratory analytical results from its Phase 4 reverse circulation drill programme at the Mushima North Project in Zambia. Eight additional drill holes have returned silver-copper-zinc intersections at the Discovery Zone and confirmed near-surface copper mineralisation at the newly identified Western Zone. Separately, Phase 5 diamond drilling commenced on 8 November 2026, targeting mineralisation at greater depths than any previous programme on the project. Investors are also awaiting imminent initial metallurgical testwork results, with a JORC Mineral Resource Estimate planned before year-end.

Key Points

  • Tertiary Minerals plc (AIM: TYM) — AIM-traded copper and precious metals explorer operating in Zambia and Nevada
  • Final eight holes from Phase 4 at Mushima North returned silver-copper-zinc intersections, with three Discovery Zone holes ending in mineralisation
  • Headline intersections include 70m at 31 g/t silver, 0.29% copper and 0.25% zinc from 10m downhole, and 68m at 27 g/t silver, 0.15% copper and 0.52% zinc from 17m downhole
  • Investors should watch for Phase 5 assay results, initial metallurgical testwork outcomes, and the maiden JORC Mineral Resource Estimate targeted before end of 2026

Phase 4 Discovery Zone Intersections Extend Mushima North Mineralisation Beyond Exploration Target Boundary

Six of the eight newly reported holes were drilled at the Discovery Zone within Target A1, where Tertiary has previously defined a JORC-compliant Exploration Target of between 15 and 30 million tonnes at 40–60 g/t silver equivalent. The announcement states that three of these six holes ended in mineralisation and that results both extended known mineralisation beyond the existing Exploration Target boundary and confirmed it remains open at depth. The strongest intersection reported is 70m at 31 g/t silver, 0.29% copper and 0.25% zinc from 10m downhole in hole 26TMNRC-078, including a higher-grade sub-interval of 6m at 84 g/t silver equivalent from 34m downhole.

Western Zone Scout Drilling at Target A1 Confirms New Near-Surface Copper Discovery at Mushima North

The remaining two of the eight holes targeted the recently identified Western Zone, also within Target A1, located 28km east of the historic Kalengwa copper-silver mine in northwest Zambia. The announcement confirms these scout holes have established the presence of near-surface copper mineralisation at this newly defined area. The best reported intersection is 24m at 0.29% copper from 19m downhole in hole 26TMNRC-076, including a higher-grade interval of 5m at 0.60% copper from 32m. Accessory minerals including bismuth, antimony, cobalt and gallium have also been intersected and are classified as critical or strategic raw materials by the European Commission, the announcement notes.

Phase 5 Diamond Drilling Tests Depth Potential Below Discovery Zone with up to 250-Metre Holes

Phase 5 drilling commenced on 8 November 2026 with approximately 1,000 metres of diamond drilling planned across up to four holes, each between 200m and 250m in length. The programme is designed to test mineralisation to a vertical depth of approximately 200m, considerably deeper than the Phase 4 maximum of 125m vertically and the current Exploration Target of approximately 95m vertically. The company intends to test for primary sulphide mineralisation at depth and to generate core samples for further metallurgical testwork. The programme is estimated to take approximately four weeks to complete, with first external laboratory assay results expected approximately six to eight weeks after submission of the initial batch.

JORC Mineral Resource Estimate Targeted Before Year-End as Metallurgical Results Await

Tertiary Minerals has stated that its plan remains to produce a JORC Mineral Resource Estimate before the end of 2026, to be undertaken in parallel with the Phase 5 deeper drill programme. Initial metallurgical testwork results are described as expected imminently and will inform that estimation work. The Mushima North Project is held through group company Copernicus Minerals Limited, which is 90% owned by Tertiary Minerals (Zambia) Limited and 10% by local partner Mwashia Resources Limited. The project operates under a non-binding technical cooperation agreement with First Quantum Minerals Limited, providing access to historic exploration data, though this agreement creates no obligation to enter into any further arrangement.