Tertiary Minerals plc (LSE:TYM) is preparing to begin a diamond drilling programme of up to 1,000 metres at its Mushima North project in Zambia, targeting deeper silver-copper-zinc mineralisation beneath the existing Discovery Zone.
The company said mobilisation to the site had commenced, with drilling expected to begin early next week. The programme will comprise up to four diamond drill holes designed to investigate the potential continuation of mineralisation at depth and assess whether the near-surface oxide deposit extends into an underlying primary sulphide system.
The planned work follows more than 3,600 metres of reverse circulation drilling completed at the Discovery Zone and forms part of Tertiary’s wider programme to establish a Mineral Resource Estimate before the end of 2026.
Diamond Drilling to Investigate Mineralisation at Depth
Tertiary Minerals plans to drill approximately 1,000 metres at Target A1, with up to four holes measuring between 200 and 250 metres each.
The holes will be inclined at approximately 60 to 70 degrees below horizontal, allowing the company to investigate mineralisation at vertical depths of up to 200 metres.
This represents a significant extension beyond the current near-surface Exploration Target, which reaches approximately 95 metres vertically, and the recent Phase 4 drilling programme, which investigated mineralisation to a maximum vertical depth of 125 metres.
The programme is designed as an initial proof-of-concept investigation into the potential continuation of mineralisation beneath the Discovery Zone.
A principal objective is to establish whether the existing oxide mineralisation transitions into a deeper primary sulphide deposit.
The drilling will also provide geological information on the structure and composition of the mineralised system, helping guide future exploration and technical studies.
Diamond drill core will be collected for additional metallurgical testing and other technical investigations.
The programme is expected to take approximately four weeks to complete.
Discovery Zone Exploration Target Contains Up to 58 Million Ounces Silver Equivalent
The Discovery Zone at Mushima North has a previously announced JORC-compliant Exploration Target of between 15 million and 30 million tonnes, with an estimated grade range of 40 to 60 grams per tonne silver equivalent.
The upper end of the Exploration Target represents approximately 58 million ounces of silver equivalent.
The target relates to a near-surface mineralised body within the oxide zone, measuring approximately 500 metres in length, 300 metres in width and up to 75 metres in thickness.
These dimensions are based on a lower cut-off grade of 25 grams per tonne silver equivalent.
The mineralisation remains open to the northwest, southwest and at depth, indicating that its full extent and geometry have not yet been established.
The Exploration Target is conceptual and does not constitute a Mineral Resource Estimate. Further exploration is required to determine whether sufficient mineralisation can be defined to support a formal mineral resource.
Tertiary intends to use its existing drilling results and outstanding laboratory data to support the preparation of a Mineral Resource Estimate before the end of the year.
Phase 4 Drilling Identifies Higher-Grade Mineralised Zone
The recent Phase 4 reverse circulation drilling programme identified a higher-grade area within the Discovery Zone.
This zone has a surface footprint measuring up to 400 metres by 150 metres, with mineralisation extending to a vertical depth of 125 metres.
The deposit remains open below the deepest drilling completed to date.
The company believes that further drilling is required to understand whether the mineralised system continues at depth and whether primary sulphide mineralisation occurs beneath the oxide zone.
Previous exploration also identified elevated concentrations of several additional elements associated with the silver-copper-zinc mineralisation.
Reported concentrations included bismuth of up to 0.53%, antimony of up to 0.22%, cobalt of 0.39% and gallium of up to 40 grams per tonne.
The potential significance of these elements has not yet been fully investigated.
The forthcoming diamond drilling programme will provide an opportunity to collect further geological and analytical information on the mineralised system.
Assay and Metallurgical Results Expected Shortly
Tertiary Minerals expects to receive the remaining laboratory assay results from its Phase 4 drilling programme imminently.
Initial metallurgical testwork results are also expected shortly.
These results will contribute to the company’s understanding of the mineralisation and its technical characteristics as it progresses towards a Mineral Resource Estimate.
During the new diamond drilling programme, samples will initially be assessed on site using portable X-ray fluorescence equipment to identify copper and zinc concentrations.
Selected mineralised intervals will subsequently be submitted to a certified external laboratory for more comprehensive analysis.
The laboratory testing will cover silver, copper, zinc, cobalt, bismuth, antimony, gallium, germanium and rare earth elements.
Samples will be submitted in batches throughout the programme.
The first laboratory results are expected approximately six to eight weeks after the initial batch is submitted.
The expanded analytical programme is intended to provide a more detailed understanding of the mineralised system and the potential presence of additional elements.
Western Zone Provides Additional Exploration Target
The Phase 4 drilling programme also identified a separate shallow copper-mineralised area approximately 900 metres west-southwest of the Discovery Zone.
The newly identified prospect, known as the Western Zone, was encountered during preliminary scout drilling.
Mineralisation at the Western Zone remains open, and its full extent has not yet been established.
The discovery provides another area for potential follow-up exploration within the wider Target A1 prospect.
Tertiary has not announced a dedicated drilling programme for the Western Zone as part of its latest update.
The immediate focus remains on testing deeper mineralisation beneath the Discovery Zone and completing the technical work required for the planned resource estimate.
Mushima North Located Near Historic Kalengwa Copper Mine
The Mushima North project is situated in Zambia’s prospective Iron-Oxide-Copper-Gold geological region.
Target A1 lies approximately 28 kilometres east of the historic Kalengwa copper-silver mine, which is currently undergoing redevelopment.
Kalengwa was historically recognised as one of Zambia’s highest-grade copper deposits, with ore averaging approximately 11% copper transported for direct smelting during the 1970s.
Mushima North is held under exploration licence 27068-HQ-LEL through Copernicus Minerals Limited.
Copernicus is owned 90% by Tertiary Minerals (Zambia) Limited and 10% by local partner Mwashia Resources Limited.
The project is also covered by a technical cooperation agreement with First Quantum Minerals Limited.
Under the arrangement, Tertiary can access historical exploration information and geological expertise relating to the area.
The agreement is non-binding and does not impose commercial restrictions on Tertiary or grant First Quantum a right of first refusal over the project.
In addition to Target A1, several other geochemical and geophysical targets remain untested by drilling.
These include targets B1, B2, B3 and C2, most of which are situated within approximately 12 kilometres of Target A1.
Managing Director Highlights Potential for Deeper Sulphide Mineralisation
Tertiary Minerals Managing Director Richard Belcher said the upcoming diamond drilling campaign represented an important next stage in the company’s exploration work at Mushima North.
“We are very excited to be back drilling again this field season at the Discovery Zone where we have made great progress and have already completed over 3,600m of Reverse Circulation drilling to support our Mineral Resource Estimation work. This programme marks our first diamond drill programme on the Project and will test for the continuation of mineralisation below the Discovery Zone and, in particular, for the potential of underlying primary sulphides.
“With the last of the laboratory results for the recent Phase 4 drilling due imminently, along with the initial metallurgical testwork results, we are then positioned for a very strong finish to this year’s Zambian field season. I look forward to providing further updates on these results and the drill programme in the coming weeks.”
The company expects the combination of new drilling, outstanding assays and metallurgical testing to provide further information on the Discovery Zone’s geological characteristics and potential development opportunities.
Tertiary Minerals Outlook
Tertiary Minerals is preparing to commence its first diamond drilling programme at Mushima North, with up to 1,000 metres of drilling planned over approximately four weeks.
The immediate objective is to determine whether silver-copper-zinc mineralisation continues beneath the existing Discovery Zone and to investigate the potential presence of an underlying primary sulphide system.
The programme will also generate drill core for additional metallurgical studies and improve the company’s geological understanding of Target A1.
Remaining Phase 4 assay results and initial metallurgical testwork findings are expected imminently, while the first results from the new drilling programme are anticipated approximately six to eight weeks after initial samples are submitted for laboratory analysis.
Tertiary continues to target completion of a Mineral Resource Estimate before the end of 2026.
The results of the forthcoming drilling will be important in determining whether deeper mineralisation warrants further exploration beyond the currently defined near-surface target.
Leave a Reply