Caledonia Mining Corporation (AIM:CMCL), which owns 64% of the Blanket Mine in Zimbabwe, said underground measured and indicated mineral resources (M&I Resources) at the operation have risen 22% to 2.178 million ounces of gold.
The estimate, effective 30 June, compares with 1.789 million ounces reported at 31 December 2023 and reflects continued underground drilling and development.
Measured resources, the highest-confidence category, increased 48%, while inferred resources fell 30% to 0.748 million ounces, a shift the company attributed largely to successful conversion into higher-confidence categories rather than depletion.
Caledonia also declared a maiden surface mineral resource estimate, identifying 22,000 ounces of gold in oxide and transitional material at 0.69 g/t, plus a further 8,000 ounces in sulphide material at 1.07 g/t.
Metallurgical test work on the oxide material has shown recoveries of up to 67% using heap-leach processing, and the company plans to build a trial heap-leach pad and mine a 10,000-tonne sample.
"This most recent mineral resource estimate at Blanket re-confirms that Blanket's mineralisation continues at depth with generally improving grades and widths and creates the potential to extend Blanket's mine-life by deepening its operations," said Mark Learmonth, chief executive officer.
Caledonia has spent $3.733 million on deep drilling at Blanket over six years, adding 1.279 million ounces of measured and indicated gold at a discovery cost of $2.92 per ounce.
Subject to environmental approvals, oxide mining and processing could begin in the first half of 2027 at a target rate of 40,000 tonnes per month.
Caledonia intends to file an NI 43-101 technical report within 45 days, including a restated Life of Mine Plan and a new mineral reserve estimate.
News Intelligence what this means for the company
Caledonia reported a 22% lift in Blanket's underground measured and indicated resources to 2.178 million ounces as of end-June, driven by successful conversion of inferred into higher-confidence categories rather than depletion. The company also declared its first surface resource estimate—30,000 ounces across oxide and sulphide material—and plans a trial heap-leach pad with first production targeted for H1 2027, extending mine life and opening a lower-cost processing route.
The resource upgrade and maiden surface estimate materially expand Blanket's reserve base and production optionality at a time when the mine has raised 2026 all-in sustaining cost guidance to $2,500–$2,700 per ounce; oxide heap-leach processing at 67% recovery could offer a lower-cost complement to underground operations and defer depletion, though the trial pad and NI 43-101 reserve restatement (due within 45 days) will be critical to validating the economic case.
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