Manuka Resources has lifted the Wonawinta Silver Mine's Ore Reserve by 28%, underpinning its imminent restart of silver and gold production with upgraded plant facilities and contracted mining operations.
- 28% increase in Ore Reserve to 7.9Mt at 50.4g/t silver
- First gold revenues expected in July 2026, silver production targeted for September quarter
- Processing plant recommissioning includes upgraded crushing and deslime circuits
- Open-pit mining with contracted operations planned for 2026
- Environmental and geotechnical assessments support recommencement
Ore Reserve Expansion Strengthens Wonawinta’s Production Outlook
Manuka Resources Limited (ASX:MKR) has updated its Ore Reserve estimate for the Wonawinta Silver Mine, reporting a 28% increase in tonnes to 7.9 million at a robust 50.4 grams per tonne silver grade. This translates to 12.8 million ounces of contained silver, a 15% rise compared to the previous reserve announced in May 2025. The upgrade comes as the company accelerates efforts to restart silver and gold production, with first gold revenues anticipated later this month and silver output targeted for the September quarter.
Recommissioning the Plant with Enhanced Processing Circuits
The Wonawinta processing plant, a key asset in the Cobar Basin, is undergoing active recommissioning. Manuka is installing upgraded crushing and deslime circuits designed to improve mill throughput and silver recovery by addressing the clay-rich nature of the ore. These plant enhancements follow metallurgical test work confirming that conventional comminution and carbon-in-leach (CIL) recovery methods remain effective, particularly after adding a desliming step to remove problematic fine clays. The plant refurbishment also includes tailings thickener and cyanide detoxification upgrades, poised to support efficient silver and gold processing.
Mining Strategy and Contracting for 2026 Operations
Mining Associates Pty Ltd completed an updated mining study, confirming the Ore Reserve is based exclusively on Measured and Indicated Mineral Resources from shallow oxide material less than 60 metres deep. The plan involves open-pit mining using conventional drill-blast-load-haul methods with a waste-to-ore strip ratio of 3.4:1. Manuka intends to contract mining services to Macmahon Contractors P/L later this year, shifting from a previous owner-operator model. The Ore Reserve includes five open cuts; Belah, Bimble, Boundary, Manuka, and Pothole; within the existing Mining Lease Boundary.
Environmental and Geotechnical Considerations Support Recommencement
Environmental assessments confirm that existing approvals remain valid for four of the pits, with no material impediments expected for recommencement. The Pothole pit may require additional approval, but prior operating history and site conditions suggest no significant hurdles. Geotechnical reviews indicate sufficient data for the Manuka and Boundary pits, while a conservative design approach has been adopted for the newer pits pending further site investigations. Manuka plans diamond drilling to address data gaps before mining these areas, potentially allowing steeper pit wall designs.
Strategic Flexibility and Growth Potential in the Cobar Basin
Beyond silver, the Wonawinta plant offers strategic optionality, already processing gold ore from Manuka’s Mt Boppy operation and capable of upgrading to handle base metal concentrates. This flexibility positions Manuka to capitalise on the rich mineral endowment of the Cobar Basin, with ongoing exploration and resource extension drilling underway. The Ore Reserve update bolsters confidence in the project’s economics, supported by a silver price assumption of US$55/oz in the reserve modelling, while current market prices exceed this.
Operational Readiness and Next Steps
Manuka’s Executive Chairman Dennis Karp highlighted the milestone, noting the pace of site recommissioning including the shipment of new crushing and deslime equipment from South Africa. With first gold revenues expected imminently and silver production scheduled for the September quarter, the company’s focus remains on safe and efficient restart of operations. The updated Ore Reserve and life-of-mine optimisation provide a solid foundation for Manuka’s next growth phase in the region.
Bottom Line?
Manuka’s expanded Ore Reserve and plant upgrades set the stage for a pivotal production restart, but upcoming geotechnical investigations and market conditions will shape the project's near-term success.
Questions in the middle?
- How will the planned geotechnical drilling at Belah, Bimble, and Pothole influence pit design and mining costs?
- What impact will current silver price volatility have on the project's economic assumptions and production scheduling?
- Can Manuka leverage the Wonawinta plant's flexibility to diversify into base metals and enhance long-term value?