THE DIAMOND PAGE — Rhonda estimates diamond grade from small

Following drilling at its Snowden, Sask., joint-venture project, Rhonda Mining (ASE) reports that Hole 93-2 contained a 1.17-metre, bedded tuff unit averaging 52 carats per 100 tonnes, with a 0.5-mm cutoff. This was arrived at by extrapolating the combined weight of only two diamonds found within 3.9 kg of core (intersecting the tuff unit). The grade extrapolation does not include nine other diamonds recovered from other zones encountered in the drill hole.

Rhonda and Aaron Oil (ASE) each hold 45% in the project, Lucky Break Gold (VSE) holds 10%, and third parties hold a 20% interest, carried to feasibility.

In reporting an average grade (carats per 100 tonnes) from two drill holes, Rhonda departed from the approach taken by senior companies exploring in the more advanced Lac de Gras region of the Northwest Territories. Typically, grade is not reported until bulk sampling has been completed, usually in the order of 200 tonnes in the exploration stage. After this stage, a decision is generally made as to whether or not to proceed with a larger bulk sample for pre-feasibility and feasibility purposes. Although grade can be predicted from geochemical analysis of indicator minerals from a kimberlitic source, such a procedure is generally viewed (by the few groups with expertise in this area) as an exploration tool for determining targets. Thus, bulk sampling is required in order that grade (as well as the size distribution and quality of the diamonds) can be estimated. “Why calculate waste?” Rhonda President Peter Gummer asked, when queried about his reporting methodology. “We are interested just in the potential economic horizon. Sure it is an extrapolation, and sure the sample is small, but the mining industry is based on extrapolation. I’m reporting results just as I would for a gold project.”

A second hole intersected a tuff unit, averaging 5.9 metres in thickness, which returned four diamonds from 17.3 kg of core. Rhonda reports that this tuff unit averaged 33 carats per 100 tonnes, with a 0.5-mm cutoff. Two other diamonds were recovered from the hole, again from other zones. Results were not reported from a third hole, which encountered only microdiamonds. The three holes were drilled roughly 300-400 metres apart, intersecting a massive unit overlain by two sequences of wave-reworked tuffs. Gummer said the overall results (from all three units) indicate grades similar to those being encountered at the adjoining Cameco-Uranerz-Monopros project at Fort a la Corne — roughly at or below 10 carats per 100 tonnes. “But I bet they have enriched zones, too,” he added.

Rhonda’s drilling is focused on a horizontal apron of layered kimberlite volcanics and sediments, occurring about 100 metres below the prairie surface. The percentage of gem-quality diamonds is believed to be well above world averages (although some are yellow or champagne-colored, and thus less valuable than white stones).

* Elsewhere in the province, lab results are awaited from the Candle Lake joint venture between War Eagle Mining and Great Western Gold. The Vancouver-listed partners say drilling has intersected what are definitely four kimberlite pipes, and not peripheral lateral structures. It is not yet known if any of the targets are diamondiferous.

Northwest Territories

* Vancouver-listed partners Ascot Resources (VSE) and Major General Resources have acquired prospecting permits and claims on Victoria Island, covering the northern extension of the Archean Slave Craton which hosts the Lac de Gras discoveries. Situated in the High Arctic, the project comprises 1.4 million acres.

Cominco (TSE) picked up ground in this region last year, based on the same notion of favorable geology and the presence of a large, regional “gravity low.” The gravity low (similar to that which is adjacent to the Lac de Gras region and thought to be indicative of deep mantle roots) is transected by linear features considered important for kimberlite emplacement. This portion of southern Victoria Island appears to be of interest to more than the aforementioned companies. A numbered Ontario company has picked up more than 7 million acres and speculation is that the unknown competitor may be an international major interested in diamonds.

* The northern part of the island is also attracting attention, but not necessarily because of its potential for hosting kimberlites. Aber Resources (TSE) now holds 2.6 million acres, covering an area considered prospective for nickel, copper and platinum group elements. Cominco also managed to pick up a few permits in this region, on the basis of a similar interest in the geological concept that the region has features in common with the Norilsk mineral district of Russia.