CALEDONIA Mining Corporation has increased the measured and indicated mineral resource at its Blanket gold mine in Zimbabwe by 22% to 2.178 million ounces, while a maiden surface resource at the K-Pits area has opened the possibility of additional near-surface gold production, Mining Zimbabwe can report.
By Rudairo Mapuranga
The underground measured and indicated resource now stands at 17.7 million tonnes grading 3.83 grammes per tonne (g/t) of gold, according to the company’s latest mineral resource estimate effective June 30, 2026.
The increase follows renewed underground exploration and development since the commissioning of Blanket’s Central Shaft in 2021, which significantly expanded the mine’s capacity to explore deeper mineralisation.
Measured resources increased by 48%, while inferred underground resources fell by 30% to 748,000 ounces. Caledonia said the changes largely reflect the conversion of resources into higher-confidence categories through drilling and development.
Chief Executive Officer Mark Learmonth said the company had invested US$3.733 million in deep drilling at Blanket over the past six years, adding 1.279 million ounces to measured and indicated resources before depletion.
Based on the company’s calculation, this represents a discovery cost of US$2.92 per ounce.
Learmonth said the latest estimate confirmed that Blanket’s mineralisation continues at depth, with grades and widths generally improving, supporting further evaluation of deeper mining.
A technical study examining options for extending Blanket below its current depth of about 1,100 metres is already well advanced, with publication expected towards the end of 2026.
K-Pits Adds Near-Surface Opportunity
The resource update also includes Blanket’s first surface mineral resource estimate following trenching and reverse-circulation drilling at the K-Pits target.
K-Pits contains an indicated surface resource of 1.251 million tonnes grading 0.76 g/t, equivalent to about 30,000 ounces of contained gold, and an inferred resource of 492,000 tonnes grading 0.89 g/t, containing about 14,000 ounces.
The discovery is significant because the mineralised zone occurs close to surface and has not been exploited by Blanket’s historic underground mining operations.
The oxide and transitional portions of the resource could potentially be treated through conventional heap leaching. Metallurgical testing on the oxide material has so far achieved recoveries of up to 67%.
Caledonia plans to prepare a trial heap-leach pad and mine a 10,000-tonne sample as it evaluates the technical and economic potential of the discovery.
Subject to the outcome of the trials and receipt of the necessary environmental approvals, the company is targeting the start of oxide mining and processing in the first half of 2027, at a proposed mining rate of about 40,000 tonnes of ore per month.
Learmonth said the surface oxide discovery could provide an opportunity for incremental gold production from shallower mineralisation.
The potential development would give Blanket another source of ore alongside its established underground operations, although production remains subject to further evaluation and regulatory approvals.
Shallower Sulphide Mineralisation Identified
Caledonia has also identified sulphide mineralisation beneath the oxide zone, with 228,000 tonnes grading 1.07 g/t in the indicated category.
The company said the shallower sulphide mineralisation could potentially provide additional production flexibility if metallurgical testing confirms that the material can be processed through Blanket’s existing plant.
Caledonia is also assessing whether the sulphide mineralisation could eventually be accessed through open-pit mining after the overlying oxide material is removed.
Further exploration is planned for 2027 to determine whether the sulphide mineralisation extends deeper.
The mineralised zone is approximately 200 metres from existing underground infrastructure on Blanket’s 7 Level, which is about 210 metres below surface, potentially providing a route for future underground access if warranted by further exploration and studies.
Deep Exploration Remains Key
The latest resource estimate reinforces Caledonia’s strategy of combining deeper underground exploration with the development of shallower mineralisation around Blanket.
The company is now using the updated resource model as the basis for a revised Life of Mine Plan and a future mineral reserve update.
Caledonia also continues exploration at its Motapa property, where drilling has identified mineralisation along approximately six kilometres of strike, adding to the company’s broader exploration portfolio in Zimbabwe.
The company intends to file an updated NI 43-101 technical report on the resource estimate with SEDAR+ within 45 days.
For Blanket, the combination of growing underground resources, continued deep exploration and the newly defined K-Pits surface resource could provide additional options for sustaining and potentially expanding gold production from one of Zimbabwe’s established gold operations.
