AIM-listed Caledonia Mining Corporation has reported an increase in mineral reserves at its Blanket gold mine in Zimbabwe.
Total proven and probable mineral reserves were up by 1% to 528 000 oz and there was a 12% increase in total measured and indicated mineral (M&I) resources to 902 000 oz.
Minxcon was commissioned by Caledonia 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-19 pandemic.
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Commenting on the news, CEO Steve Curtis 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 1% increase in the proven and probable mineral reserves and a 12% increase in M&I after mining depletion of 84 925 oz is a continuation of securing the long-term future of Blanket.
“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 oz 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 stands at 8.5 million tonnes at a grade of 3.29 g/t, a 12% reduction in grade although the updated mineral resource grade remains consistent with current Blanket run of mine grade.
Resource continues to grow
Meanwhile, inferred mineral resources at Blanket have decreased by 10% from 963 000 oz, as at July 2018, to 866 000 oz as at 1 January 2020. The decrease is due to approximately 18% 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% since 2011 despite mining over 400 000 oz over this period.