Modern Mining June 2016

WEST AFRICA

Baoulé bulk sampling completed

west lobes were sampled and processed sepa- rately, which did confirm a difference in grade between the two. Some 46 561 tonnes were pro- cessed from the eastern lobe and 56 555 tonnes from the western lobe. In all, 11 808 carats have been recovered to date from Baoulé, giving an average grade of 11,4 cpht. However, says Stellar, it is clear that the eastern lobe has a higher grade at 13,3 cpht than the western lobe (at 9,8 cpht). The com- pany believes this could be a consequence of different kimberlite types or processing efficien- cies, since it was noted that the western lobe did yield a lower percentage of -7 sieve stones (<1,83 mm) compared to the eastern lobe. A total of 929 stones greater than 1 carat have been recovered including numerous high value gem and fancy coloured (yellow) diamonds of up to 12 carats in size. The biggest diamond recovered thus far is a 55-carat stone. Although it is of low quality, Stellar says it confirms its belief that the Baoulé pipe is a source of the large diamonds for which the Aredor area is renowned. Three diamond sales have been held to date. Some 8 400 carats have been sold realising

AIM-listed Stellar Diamonds has completed its 100 000-tonne bulk sampling and trial mining programme at its 75 %-owned Baoulé kimberlite pipe in Guinea. Some 11 808 carats were recovered at an average grade of 11,4 cpht at a +1,25 mm cut-off.

B aoulé is a 5 ha pipe which was discovered in the late 1990s by a Canadian company. The project is located in the heart of the Aredor diamond district of Guinea which has historically yielded very large, high value diamonds from alluvial mining. Stellar ac- quired the project with a local partner just over three years ago and launched the trial mining programme in November 2014. The geology of the pipe is complicated in parts with what seem to be multiple intrusions and brecciated contact zones in both lobes, with the western lobe in particular hosting a number of late stage and cross-cutting kimberlite dykes. For the purposes of evaluation, it was not pos- sible to separate and process separately each kimberlite lithology. However, the east and

Approaching the end of mining in the Western Lobe open pit (photo taken in May this year).

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42  MODERN MINING  June 2016