Caledonia Mining Blanket Mine M&I Gold Resources Rise 22% to 2.178 Million Ounces
- Underground M&I gold resources rose 22% to 2.178 million ounces at 3.83 g/t
- Measured resources surged 48% as inferred resources fell 30% due to conversion
- Maiden surface estimate declares 30,000 ounces of indicated gold resources
- Discovery cost for added underground ounces calculated at $2.92 per ounce
- Surface oxide heap leach operations may start in H1 2027 pending approvals
*this image is generated using AI for illustrative purposes only.
Caledonia Mining Corporation Plc (NYSE: CMCL) reported a 22% increase in underground measured and indicated mineral resources at its Blanket mine in Zimbabwe, driven by successful deep drilling programs.
The updated estimates, effective June 30, 2026, reflect the conversion of lower-confidence inferred resources into higher-confidence categories following extensive exploration since 2021.
Underground Resource Expansion
The company increased its underground measured and indicated (M&I) resources to 2.178 million ounces of gold contained in 17.674 million tonnes at a grade of 3.83 g/t. This represents a significant upgrade from the December 31, 2023 estimate of 1.789 million ounces.
Measured mineral resources saw the strongest growth, rising 48% to 1.090 million ounces. Indicated resources grew modestly by 3% to 1.088 million ounces. Conversely, inferred resources declined by 30% to 0.748 million ounces, primarily due to their conversion into measured and indicated categories rather than depletion.
| Classification | Tonnes (kt) | Grade (g/t) | Ounces (koz) | Variance (%) |
|---|---|---|---|---|
| Measured Total | 8,352 | 4.06 | 1,090 | +48 |
| Indicated Total | 9,321 | 3.63 | 1,088 | +3 |
| M&I Total | 17,674 | 3.83 | 2,178 | +22 |
| Inferred Total | 6,940 | 3.35 | 748 | -30 |
Maiden Surface Estimate
Caledonia also announced a maiden surface mineral resource estimate for Blanket, identifying potential for low-cost heap leach processing. The surface indicated resources total 30,000 ounces of gold.
This includes:
- Oxide material: 5,000 ounces in 180 kt at 0.91 g/t
- Transitional material: 17,000 ounces in 844 kt at 0.64 g/t
- Sulphide material: 8,000 ounces in 228 kt at 1.07 g/t
Inferred surface resources add another 14,000 ounces across oxide, transitional, and sulphide zones.
What the Numbers Show
The data reveals a strategic shift in resource confidence. While total underground tonnes increased by only 16%, the grade improved by 5%. More significantly, the 48% surge in measured resources contrasts with the 30% drop in inferred resources. This divergence indicates that Caledonia’s $3.733 million investment in deep drilling over six years has successfully de-risked the deposit by converting speculative inferred zones into bankable measured categories, reducing geological uncertainty for future reserve estimation.
Operational Outlook
CEO Mark Learmonth noted that the discovery cost for the added 1.279 million ounces was $2.92 per ounce. A technical study to evaluate deepening operations below 1,100 meters is expected late in 2026. Additionally, metallurgical test work on surface oxide material showed recoveries up to 67%, with potential heap leach operations targeting commencement in the first half of 2027.
How might the successful conversion of inferred resources to measured categories impact Caledonia's ability to secure project financing or debt covenants for the Blanket mine expansion?
What are the potential regulatory and community engagement challenges associated with deepening operations below 1,100 meters in Zimbabwe's mining sector?
Given the $2.92 per ounce discovery cost, how does Caledonia's capital efficiency compare to regional peers, and will this influence future exploration budget allocations?
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