Having completed a bulk-sampling program at the Fort la Corne diamond project in Saskatchewan, Monopros is preparing to treat the samples at its Canadian plant before shipping them to the South African laboratory of parent company
The project is a joint venture, owned 30% by each of
In the recent program, two large-diameter reverse-circulation holes were drilled into each target, recovering a total of 64 tonnes of kimberlite.
Composite grab samples collected over both 1- and 6-metre intervals of the holes will be analyzed for microdiamonds as well as macrodiamonds, and a composite grab sample from hole 147-1, which was drilled in 1991, may also be processed for micros.
The microdiamond results will be used to augment the database to enable more reliable grade predictions for commercial-size diamonds in kimberlite bodies 147 and 220.
The project comprises 25,488 ha in the central part of the province, 80 km east of Prince Albert. Since 1989, when drilling began, 69 kimberlite bodies has been discovered. Fifty-five of these are confirmed to be diamondiferous, with 34 of the bodies having yielded macrodiamonds (defined here as stones exceeding 1 mm in at least one dimension).
The primary objective of the most recent program was to test the 147 and 220 kimberlites. Previous work on the 147 body yielded 58 micros from 34 kg of sampled drill core in hole 143-3. A 20-tonne mini-bulk sample had returned 1.5 carats of diamonds, for a preliminary indicated grade of 7.5 carats per 100 tonnes.
The 220 kimberlite was last drilled in 1997. Microdiamond analysis of a 78.4-kg sample revealed 159 stones weighing 0.039 carat, including a 1.66-mm clear yellow diamond. A further 15.4 tonnes of drill sample returned 20 macros weighing 1.27 carats, including a 0.7-carat stone described as white with abundant inclusions. A preliminary grade of 4.6 carats per 100 tonnes was calculated based on a theoretical mass of 27.5 tonnes.
Based on limited drilling and geophysical modeling, kimberlite 147 is considered to contain more than 490 million tonnes, whereas the 220 body is estimated at 80 million tonnes.
Early-stage evaluations of the Fort a la Corne diamonds were conducted last year by Antwerp, Belgium-based Luc Rombouts of Terraconsult, who examined a small parcel of 720 stones weighing a total of 37.3 carats. The average value was estimated at US$32 per carat, based on prices at the end of 1997. The individual kimberlite bodies varied from US$3 to US$89 per carat.
In news related to the Fort a la Corne area, Kennecott Canada Exploration has pulled out of the Candle Lake joint venture after receiving disappointing results from the initial processing of 7.6 tonnes of a mini-bulk drill sample collected from kimberlite C29/30. A total of 0.28 carat of diamonds was recovered, suggesting an effective grade of 3.7 carats per 100 tonnes. The two largest stones recovered weighed just 0.08 carat each.
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