EXPLORING FOR DIAMONDS AND THE NORTH — Canadian diamond

Although the current level of diamond exploration in Canada is unprecedented, the hunt began as early as 1863 after diamonds were found in glacial drift around the Great Lakes.

Exploration was sporadic until 1946, when geologists reported the discovery of Canada’s first kimberlite while drilling for gold in Michaud Twp., near Kirkland Lake, Ont.

Gradually, the search moved northwest along a linear trend stretching as far as the James Bay Lowlands. Over time, several gem-quality diamonds were found in glacial drift around the Great Lakes. The largest of these, weighing 33 carats, was plucked from an esker near Peterborough, Ont.

Interest spread to Saskatchewan in 1948, when a prospector claimed to have found five stones in a kimberlite in the northern part of the province. According to an article written by Charles Fipke, now chairman of Dia Met Minerals (TSE), and published in the September, 1990, edition of the Canadian Mining Journal, many thousands of small diamonds have been recovered from kimberlites in the Northwest Territories, Ontario, Saskatchewan, Colorado and Michigan as well as from eight lamproites (including the Prairie Creek lamproite in Arkansas).

But until the 1991 discovery at Lac de Gras, N.W.T., diamond exploration in Canada — dominated by Monopros, the secretive exploration arm of De Beers of South Africa — was poorly documented and shrouded in mystery. Some of the better known primary finds include:

* Somerset Island, N.W.T., early 1970s. Using air photos, Diapros (the predecessor to Monopros) and Cominco (TSE) delineated a cluster of kimberlite pipes. Six micro-diamonds were subsequently recovered from the pipes. * Southern Rocky Mountains, B.C., 1980. Between 1976 and 1980, Cominco explored a 17,000-square-mile area around a known kimberlite pipe in the Rockies but came up with nothing. Using more advanced techniques, Superior Oil later discovered two large diamond-bearing pipes in the area. * Kirkland Lake, Ont., 1984-1988. Monopros and Lac Minerals (TSE) drilled and sampled several kimberlite pipes and dykes in Arnold, Bisley, Bucke and Clifford twps. A total of 16 stones, ranging in weight from 0.005 carats to 0.17 carats, were recovered from four pipes. To date, about 14 kimberlite intrusions, eight of which carry microdiamonds, are known to occur in the area.

* Fort a la Corne, Sask., 1988. Staking by Monopros sparked a rush to the Fort a la Corne area in 1988. In 1991, partners Cameco (TSE) and Uranerz Exploration and Mining reported finding 160 diamonds within 15 different pipes. Most of the bulk samples graded less than 2 carats per 100 tons. Ongoing sampling, in partnership with Monopros, continues to yield small, gem quality diamonds.

* Lac de Gras, N.W.T., 1991. Dia Met touched off Canada’s largest staking rush with the discovery of 81 small diamonds measuring less than 2 mm in diameter from a 59-kg sample of the Point Lake kimberlite. Subsequent bulk-sampling indicated a grade of about 60 carats per 100 tons. Drilling by various companies in the area has since uncovered at least 30 pipes, many of which are diamondiferous.

* Le Tac Twp., Que., 1993. Partners Monopros and Explorations Minieres du Nord (ME) recently found a microdiamond and numerous G10 garnets in a kimberlite pipe at Le Tac Twp. in northwestern Quebec. Most of the surrounding area has now been staked.

Diamondiferous pipes are also reported to have been found in the Mackenzie Mountains of the Northwest Territories, and on Ile Bizard, near Montreal, Que., but information on these finds is sketchy.

— The author is a former staff writer for The Northern Miner.