MANUKA RESOURCES LTD (ASX:MKR) has increased the Probable Ore Reserve at its 100%-owned Wonawinta Silver Mine in New South Wales by 28%, strengthening the foundation for a planned restart of gold and silver processing operations this quarter.
The updated reserve stands at 7.9 million tonnes grading 50.4 grams per tonne silver for 12.8 million ounces of contained silver.
This represents a 28% increase in reserve tonnes and a 15% rise in contained silver compared with the estimate announced in May 2025.
Manuka is currently recommissioning the Wonawinta processing plant, with first gold revenue expected later in July and silver production targeted to begin during the September 2026 quarter.
Updated reserve supports restart plans
The new Ore Reserve comprises shallow, predominantly oxide mineralisation located less than 60 metres below surface and is based entirely on Measured and Indicated Mineral Resources.
The reserve estimate covers 7.9 million tonnes at 50.4 g/t silver and is expected to be mined using conventional open-pit drill, blast, load and haul methods.
Total material movement is estimated at 34.1 million tonnes, resulting in a waste-to-ore strip ratio of 3.4:1.
Mining Associates Pty Ltd completed the updated mining study, including pit optimisation, mine design, scheduling and economic analysis.
The reserve pit optimisation was based on a silver price of US$50 per ounce, while financial modelling used US$55 per ounce and an AUD/USD exchange rate of 0.70.
The Ore Reserve includes the Belah, Bimble, Boundary, Manuka and Pothole open pits, all of which are situated within the existing mining lease.
Manuka executive chair Dennis Karp said the updated study provided greater confidence in the proposed restart.
“Completion of the updated mining study marks another important milestone as Manuka progresses towards the recommencement of mining and processing operations at Wonawinta,” Karp said.
“The revised Ore Reserve provides additional confidence in the production restart while highlighting the quality of the existing Mineral Resource and the potential for further optimisation as mining recommences.”
Plant refurbishment nearing completion
Wonawinta is fully permitted and the existing processing plant and supporting infrastructure are in the final stages of refurbishment and upgrade.
Recommissioning work includes recruitment, operational readiness activities, finalisation of contracts and the installation of upgraded crushing and de-slime circuits.
The new crushing and de-slime equipment has been fabricated by Bond Equipment in South Africa and is being shipped to site.
“As we move towards first gold revenues later this month, with silver production due to commence during the September quarter, our focus remains on safely recommissioning the operation and delivering the next phase of growth for Manuka,” Karp said.
The processing plant was last operated in 2024 and is considered a strategic asset within the Cobar Basin due to its ability to process silver, gold and potentially base metal material.
Larger resource offers further upside
Wonawinta’s broader Mineral Resource remains unchanged at 38.3 million tonnes grading 41.3 g/t silver for 51 million ounces of contained silver.
Only Measured and Indicated Resources were assigned value during the reserve optimisation process, while Inferred Resources were treated as waste.
This leaves scope for future drilling, optimisation and resource conversion to potentially extend the mine plan and increase the reserve base.
About Manuka Resources
Manuka Resources is focused on precious metals and critical minerals assets.
Its portfolio includes the Wonawinta Silver and Base Metals Project and the nearby Mt Boppy Gold Project in the Cobar Basin of New South Wales.
The company also owns the Taranaki vanadium-titanium-iron project offshore New Zealand.