Caledonia Mining Corporation Plc has announced an increase in the underground measured and indicated mineral resources at Blanket Mine in Zimbabwe, alongside the operation’s first surface mineral resource estimate. The updated underground estimate contains 2.178 million ounces of gold in 17.7 million tonnes at a grade of 3.83 g/t, representing a 22% increase.
#Underground resource estimate
The revised underground estimate has an effective date of June 30, 2026 and was prepared under Canada’s National Instrument 43-101. The measured and indicated resource increased from 1.789 million ounces at December 31, 2023 to 2.178 million ounces.
Measured resources rose by 48%. Inferred underground resources decreased by 30% to 0.748 million ounces, compared with 1.061 million ounces at December 31, 2023. Caledonia said the reduction in inferred resources largely reflected the conversion of material into the measured and indicated categories, rather than depletion alone.
The updated estimate incorporates underground development sampling, run-of-mine drilling and long-hole exploration drilling. Caledonia said the recent drilling has focused on the southern sections of the underground mineralised zones, with work in the northern areas scheduled over the next two years.
Chief Executive Officer Mark Learmonth said Caledonia had invested $3.733 million in deep drilling at Blanket over the last 6 years following the commissioning of the Central Shaft in 2021. He said this work had added 1.279 million ounces of measured and indicated gold ounces before depletion, at a discovery cost of $2.92 per ounce.
#Maiden surface resource
Caledonia has also reported its first surface mineral resource estimate for Blanket after surface trenching and reverse circulation drilling. The estimate covers oxide, transitional and sulphide material.
Indicated oxide and transitional resources total 22 thousand ounces of gold in 1,024 kt of ore at a grade of 0.69 g/t. A further indicated sulphide resource contains 8 thousand ounces of gold in 228 kt of material at a grade of 1.07g/t.
Because this is the first surface estimate reported for Blanket, Caledonia has provided no comparison with an earlier estimate. The company said the exploration programme was aimed primarily at identifying shallow oxide and transitional material for evaluation of heap-leach processing.
#Planned technical and operating work
Caledonia intends to submit an NI 43-101 technical report to SEDAR+ within 45 days. The report is expected to include a restated Life of Mine Plan and a new mineral reserve estimate. The company also intends to file a technical report summary with the SEC under S-K 1300.
Learmonth said a technical study examining options for deepening Blanket below 1,100 meters below surface is expected to be published towards the end of 2026.
Learmonth also said oxide mining and processing may begin in the first half of 2027, subject to successful evaluations and the receipt of the necessary environmental approvals. He said Caledonia would prepare a trial heap-leach pad and mine a 10,000 tonne sample, with a target mining rate of 40,000 tonnes of ore per month.
The company said the small sulphide resource beneath the oxide material requires further assessment. Learmonth said Caledonia would test whether it could be processed through Blanket’s existing metallurgical plant. Further exploration is planned during 2027 to determine whether the sulphide mineralisation extends deeper.
#Resource classification and cautions
The estimates are reported under NI 43-101 on a 100% project basis and on an in-situ basis. Caledonia states that mineral resources are not mineral reserves and have no demonstrated economic viability. The company also cautions that there is no certainty that any part of an inferred resource will be upgraded to an indicated or measured category or converted into a mineral reserve.
The announcement identifies risks involving the accuracy of resource and reserve estimates, variations in mined grades and recoveries, future exploration and drilling, sampling and assay reliability, metallurgical test work, project costs, commodity prices, exchange rates and delays in obtaining governmental or environmental approvals. It also cites environmental, safety, regulatory and political risks, as well as uncertainty around mining inputs, labour and project timing.
#Key Takeaways
- Blanket’s underground measured and indicated resources increased by 22% to 2.178 million ounces of gold.
- The underground estimate contains 17.7 million tonnes at a grade of 3.83 g/t.
- Caledonia reported a maiden surface estimate including 22 thousand ounces of indicated oxide and transitional resources and 8 thousand ounces of indicated sulphide resources.
- An NI 43-101 technical report is intended to be filed with SEDAR+ within 45 days and is expected to include a restated Life of Mine Plan.
- The reported resources are not mineral reserves and have no demonstrated economic viability.
#What has Caledonia Mining Corporation Plc announced at Blanket Mine?
Caledonia Mining Corporation Plc announced that Blanket Mine’s underground measured and indicated mineral resources had increased by 22% to 2.178 million ounces of gold, contained in 17.7 million tonnes at a grade of 3.83 g/t. It also announced a maiden surface mineral resource estimate.
#Which securities markets and ticker symbols are identified for Caledonia Mining Corporation Plc?
The announcement identifies Caledonia Mining Corporation Plc under NYSE AMERICAN:CMCL, AIM:CMCL and VFEX:CMCL.
#What are the reported underground mineral resource figures?
The underground measured and indicated estimate increased by 22% to 2.178 million ounces, compared with 1.789 million ounces at December 31, 2023. Measured resources increased by 48%. Inferred underground resources fell by 30% to 0.748 million ounces, compared with 1.061 million ounces at December 31, 2023. Caledonia said the decline largely reflected conversion into higher-confidence measured and indicated categories rather than depletion alone.
#What surface mineral resources have been declared?
The maiden surface estimate includes 22 thousand ounces of indicated gold in 1,024 kt of oxide and transitional material at a grade of 0.69 g/t. It also includes 8 thousand ounces of indicated gold in 228 kt of sulphide material at a grade of 1.07g/t. No earlier comparison is available because this is Blanket’s first reported surface mineral resource estimate.
#Do the reported mineral resources represent mineral reserves or demonstrate economic viability?
No. Caledonia states that mineral resources are not mineral reserves and have no demonstrated economic viability. It also says there is no certainty that all or any part of an inferred mineral resource will be upgraded to an indicated or measured category or converted into a mineral reserve. The estimates are reported under NI 43-101 on an in-situ basis.
#What further work and approvals does the announcement describe?
Caledonia intends to file an NI 43-101 technical report with SEDAR+ within 45 days, including a restated Life of Mine Plan and a new mineral reserve estimate. The company also intends to file a technical report summary with the SEC under S-K 1300.
Learmonth said a technical study assessing the deepening of Blanket below 1,100 meters below surface is expected towards the end of 2026. He also said oxide mining and processing may commence in the first half of 2027, subject to successful evaluations and receipt of the necessary environmental approvals.
#What risks and uncertainties does the announcement identify?
The announcement cites uncertainty around resource and reserve estimates, mined ore grades and recoveries, future exploration, drilling, sampling, assay data and metallurgical test work. It also identifies possible changes in capital and operating costs, exchange rates and commodity prices, along with delays in or failure to obtain governmental, environmental or other approvals.
Additional risks listed include project delays, environmental, safety and regulatory issues, political risk, the availability and cost of mining inputs and labour, and the speculative nature of mineral exploration, development and mining. Caledonia also notes that technical and scientific disclosure prepared under NI 43-101 may differ from information prepared under the SEC’s S-K 1300 requirements.
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