Diavik bulk sample reflects past results

Initial processing of an underground bulk sample from the A-154 South pipe at the Diavik diamond project in the Northwest Territories is returning grades comparable to an earlier mini-bulk drill sample.

Kennecott Canada, which holds a 60% interest in the project, situated near Lac de Gras, has processed 210 tonnes to date. Joint-venture partner Aber Resources (TSE) holds the remaining 40%.

While the first two rounds of advancement into the kimberlite yielded 85 carats from a 46-tonne sample, for a grade of 1.8 carats per tonne, the subsequent processing of 164.4 tonnes returned 688.4 carats for a grade of 4.2 carats per tonne. The initial 46 tonnes were heavily diluted with surrounding wall rock and grout cement.

The largest stone recovered to date weighs 5.5 carats, and the largest gem-quality diamond weighs 4.05 carats. The 210 tonnes represent an advance of 42 ft. into the kimberlite.

Last year, large-diameter drilling recovered 56.5 tonnes, which returned a grade of 4.5 carats per tonne. The diamonds were valued at US$58.17 per carat, giving an overall value of US$262 per tonne.

Surface drilling has delineated a resource of 8.4 million tonnes to a depth of 250 metres. Aber believes the A-154 South pipe could contain as much as 20 million tonnes if projected to a depth of 650 metres.

Kennecott, as operator, has driven a 1-km long decline into the A-154 South pipe to a vertical depth of 155 metres, with the objective of taking a 3,000-tonne bulk sample, enough to provide a representative diamond sample of at least 10,000 carats.

To date, about 1,390 tonnes of kimberlite have been mined from three headings. The material is being trucked via winter road to Kennecott’s diamond recovery plant in Yellowknife.

In the meantime, large-diameter drilling, under way on the A-418, A-154 North and A-21 kimberlite pipes, is expected to recover 180 tonnes in total by the end of the winter drilling season. The drilling is aimed at establishing a definitive grade for the pipes.