Releasing the Mineral Resource Update for the Karowe Mine in Botswana, prepared as per NI 43-101 norms, Lucara Diamond Corp said that the results support both the continued recovery of large high value diamonds from open pit mining at the project and the likelihood for underground mining until at least 2036. 

The updated Mineral Resource includes a recoverable Indicated Mineral Resource of 7.9 million carats hosted in 57.85 million tonnes at an average grade of 13.7 cpht with an average modeled diamond value of US$ 673 per carat.

A significant aspect of the update is the successful reclassification from Inferred to Indicated Resources for the AK06 kimberlite and modifications to the internal geological model for the South Lobe of AK06 kimberlite result in the recognition of the EM/PK(S) unit as the volumetrically dominant unit at depth within the South Lobe.

This has resulted in an increase in the in situ Indicated Mineral Resources (as at end 2017) by 44% and a 54% rise in the remaining Indicated Mineral Resource for the South Lobe of the AK06 kimberlite from 4.42 Mct to 6.78 Mct.

Further, 51% of the remaining South Lobe recoverable Indicated carats and 35% of the tonnage is attributable to the EM/PK(S) unit, in comparison with 12% carats and 8% tonnage from the previous estimate.

The EM/PK(S) controlled sample yielded a grade of 17cpht with 9.5 weight % specials (>10.8ct), 47 diamonds greater than 10.8ct including 1 >100 carats and 6 diamonds > 50 carats in weight

Lucara stated that the Karowe Mine has been in commercial production since July 2012. The mine has produced and sold over 2 million carats from 13.9 million tonnes of processed kimberlite at an average sales price of $US 606/carat and is firmly established as one of the world's foremost producer of large and high value diamonds. Historical recoveries from the EM/PK(S) have included several large and high value diamonds such as the 1109 carat Lesedi La Rona and the 813 carat Constellation

Eira Thomas CEO, said, "Going forward, the Karowe mine plan is dominated by South Lobe ore, with the high grade, high value EM/PK(S) unit becoming increasingly prevalent as we mine deeper.  We now understand that some of Karowe's large, high value diamonds originated from the EM/PK(S) unit including the historic 1109 carat Lesedi La Rona and the 813 carat Constellation which sold for a record US$63 million.  This resource update supports the continued recovery of large high value diamonds from the South Lobe throughout its remaining open pit mine life and the likelihood for underground mining until at least 2036.  Feasibility work assessing the potential for underground mining, including hydrogeological and geotechnical drilling together with several mining trade off studies is ongoing."

The Company said that the new results will be used for mine planning and to support the preparation of current feasibility-level studies for the potential development of an underground mine, after the completion of the current open pit mine,

The updated Mineral Resource Estimate was completed by Mineral Services Canada Inc, Lucara reported.

Pic caption: The Karowe open pit mine

Pic courtesy: Lucara Diamond Corp