Caledonia Mining Corporation Plc (LON:CMCL) has announced an upgrade to the Mineral Resource and Mineral Reserve base at its 64 per cent owned subsidiary, the Blanket Mine in Zimbabwe. Total Proven and Probable Mineral Reserves increased by one per cent to 528,000 ounces (17 per cent increase including depletion of 84,925 ounces since last update) and a 12 per cent increase in total Measured and Indicated Mineral Resources to 902,000 ounces (23 per cent increase including depletion).
The report fully validates the Company’s medium term production profile targeting 80,000 ounces per annum from 2022.
Minxcon (Pty) Ltd were commissioned by the Company to produce an updated Mineral Resource and Mineral Reserve estimation based upon existing data, but reflecting the completion of Central Shaft, historic mining and taking the opportunity to further digitise data and embrace the latest analytical tools. The report was commissioned based upon data struck at 1 January 2020, albeit its completion was delayed by the impacts of the Covid pandemic.
Commenting on the Mineral Resource and Mineral Reserve update, Steve Curtis, Chief Executive Officer said:
“Today’s announcement marks an additional milestone in the long track record of growing Mineral Resources and successfully converting Inferred Mineral Resources into M&I to keep extending the life of mine at Blanket since its inception in 1906. A one per cent increase in the Proven and Probable Mineral Reserves and a 12 per cent increase in M&I after mining depletion of 84,925 ounces is a continuation of securing the long-term future of Blanket.
“The reduction in Inferred Mineral Resources is due partly to successful conversion to M&I, at approximately 18 per cent, and partly the lack of deep level exploration over the last 12 months, awaiting the development of new drilling platforms on the lower levels via the recently-commissioned Central Shaft. The latest geological information available, combined with a lower Mineral Resource cut-off grade, from 2.1 grammes per tonne (“g/t”) to 1.5 g/t, due to the higher gold price, added lower grade Mineral Resources, resulting in a reduction in the Inferred Mineral Resources grade. These numbers are independently determined and available in the latest technical report which is being filed today on SEDAR. The lower Inferred Mineral Resources grade is broadly consistent with Blanket’s recently achieved grade, which demonstrates that Blanket can comfortably mine at this grade.
“Now that the Central Shaft is completed, we will have the ability to do more deep level exploration and we expect to replace the depleted Mineral Resources as we continue to go deeper, extending the life of mine while achieving the 80,000 ounce target from 2022 onwards.”
The Mineral Reserve grade of 3.38 g/t remained unchanged from July 2018 with the Mineral Reserve cut-off grade also remaining unchanged at 2.1 g/t.
Total M&I now stand at 8.5 million tonnes at a grade of 3.29 g/t, a 12 per cent reduction in grade although the updated Mineral Resource grade remains consistent with current Blanket run of mine grade.
Inferred Mineral Resources at Blanket have decreased by 10 per cent from 963,000 ounces, as at July 2018, to 866,000 ounces as at January 1, 2020. As mentioned above, the decrease is due to approximately 18 per cent of Inferred Mineral Resources being converted to the M&I category and the lack of deep drilling exploration over the last 12 months awaiting the development of new drilling platforms on the lower levels via the recently commissioned Central Shaft. Lower grade Inferred Mineral Resources were added due to lowering the Mineral Resource cut-off grade to 1.5 g/t from 2.1 g/t as a result of a higher gold price. Total Inferred Mineral Resources now stand at 8.5 million tonnes at a grade of 3.17 g/t. The reduction in Mineral Resource grade is due to a combination of the Mineral Resource cut-off grade being lowered, as mentioned, adding lower grade Mineral Resources in all categories, and an updated interpretation of the ore bodies with additional geological information.
Blanket’s Mineral Resources have grown by approximately 86 per cent since 2011 despite mining over 400,000 ounces over this period.
The table below compares the January 2020 Mineral Resources with the previously stated July 2018 Mineral Resources (refer to news release filed on SEDAR on September 20, 2018). The January 2020 Mineral Reserves are compared to the previously stated July 2018 Mineral Reserves (refer to Mineral Reserve Calculations in the Company’s annual report on Form 20-F filed on SEDAR on 29 March 2021).
Blanket Total Mineral Resources and Mineral Reserves (effective January 1, 2020)
|Mineral Resource Category||Tonnes (Mt)||Tonnes (Mt)||Grade (g/t)||Grade (g/t)||Contained Gold (koz)||Contained Gold (koz)||Contained Gold (koz)|
|Mineral Reserve Category||Tonnes (Mt)||Tonnes (Mt)||Grade (g/t)||Grade (g/t)||Contained Gold (koz)||Contained Gold (koz)||Contained Gold (koz)|
|Total Proven & Probable||4.8||4.86||3.38||3.38||523||528||1%|
All Mineral Resources for Blanket are shown on a 100% basis; Caledonia owns 64% of Blanket.
Mineral Resources (2020)
1. Cut-off applied 1.5 g/t.
2. No Geological loss applied for Measured, 5% for Indicated and Inferred.
3. Gold price: USD1,600/oz.
4. Mineral Resources are stated inclusive of Mineral Reserves.
5. Mineral Resources are reported as total Mineral Resources and are not attributed.
6. All orebodies are depleted for mining.
Mineral Reserves (2020)
1. Mineral Reserve cut-off of 2.1 g/t applied.
2. The gold price that has been utilised in the economic analysis to convert diluted Measured and Indicated Mineral Resources in the LoM plan to Mineral Reserves is an average real term price of USD1,660/oz over the LoM.
3. Mineral reserves are reported as total Mineral Reserves and are not attributed.