THE DIAMOND PAGE — Sable kimberlite pipe replaces Leslie at diamond project in N.W.T.

At the NWT Diamonds project near Lac de Gras, the richer Sable pipe has replaced the Leslie pipe as a target of mining.

A 1,096-tonne sample from the Sable pipe returned 1,070.3 carats, for a grade of 0.98 carat per tonne, a value of US$64 per carat and a preliminary value of US$63 per tonne.By comparison, the Leslie pipe graded 0.32 carat and has a value of US$28 per tonne.

A final feasibility study by Australian mining giant BHP, which owns a 51% interest in the project, calls for five pipes to be mined: Panda, Misery, Koala, Fox and Sable.

The study says the Leslie pipe, and two others that have been bulk-sampled, “may have economic potential” and that another five pipes “warrant additional sampling.”

Dia Met Minerals (DMM-T) owns 29% of the project, while the remaining 20% is split between Dia Met founder Charles Fipke and fellow-geologist Stewart Blusson.

The study calls for a minimum minelife of 17 years, though 25 is the unofficial estimate. Regulatory approvals are in place and startup of the planned $1.2-billion mine is scheduled for late 1998.

The final environmental agreement was signed by the federal and territorial governments, BHP and four aboriginal groups.

Mine site construction, including permanent housing, is already under way, and fuel and construction materials are being delivered over a winter road.

Prestripping will begin this spring.

Since Fipke discovered the first Point Lake kimberlite pipe in 1991, the joint venture has spent $200 million, identifying 77 kimberlite pipes to date. Twenty of those have been sampled.

Over its mine life, NWT Diamonds is expected to process 133 million tonnes of ore from the five diamond-bearing pipes through a combination of open-pit and underground mining.

Capital costs prior to startup are pegged at $750 million, and the project is expected to generate $400-500 million in annual revenue.