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MODERN MINING
June 2016
WEST AFRICA
feature
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
Baoulé
bulk sampling completed
Approaching the end of
mining in the Western Lobe
open pit (photo taken in
May this year).
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.
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