Resources and reserves
The Letšeng kimberlites are unique and have been a source of intrigue for geologists since their discovery. Not only are the diamond populations atypical, but the way the pipes were formed and their emplacement history is rather unusual. Several features of the two Letšeng pipes (Main and Satellite) differentiate them from the Kimberly-type Pyroclastic Kimberlites and impact our understanding of the distribution diamonds within the pipes.
Since mid-2013, the geological team at Letšeng has been working with a team of leading kimberlite experts from Canada and South Africa to gain a deeper understanding of the relationships between the various kimberlite types within each pipe and to differentiate higher grade varieties from those with high value (containing large and abundant Type II diamonds).
Although Letšeng demonstrates broad scale consistency year on year in terms of price and average stone size for each of the kimberlite domains, the objective of the resource development programme is to gather data on local variability within each domain to improve large stone predictability and calibrate expectations of what each domain and subdomain can reasonably be expected to yield in terms of grade, average stone size, number of +100 carat stones and average price.
No additional resources and reserves have been added since the last update carried out by Venmyn Deloitte in 2015 (click here to view the 2015 Letšeng’s independent report and detailed statements). The priority is firming up on the existing resource base and making appropriate operational and infrastructural adjustments to extract maximum value.
Since mining operations began at Ghaghoo, the focus was on confirming the De Beers historical resource and reserve estimates for the higher grade VKSE domain. Mining started in the south eastern portion of the pipe in the relatively undiluted VKSE ore and progressed towards the central zone containing abundant country rock dilution
Owing to the decline in prices for the Ghaghoo diamonds it became apparent that the sustainability of the mine, in its current form, was not financially viable. No further resource evaluation work was carried out at Ghaghoo during the commissioning and ramp-up phases before the decision was taken to place the mine on care and maintenance. Consequently, there has been no update to the Resource and Reserve statement published by Venmyn Deloitte in 2014 (click here to view the 2014 independent report and detailed statements).