Microdiamond analysis of material pulled from the NW dyke on the Camsell Lake property in the Northwest Territories indicates that microdiamond counts are constant over the area sampled.
The project, situated 220 km northeast of Yellowknife, N.W.T., is held jointly by
The kimberlite samples were obtained from 109 drill holes, as well as representative samples obtained from bulk-sample pits 3 and 4.
Winspear reports that its data, combined with the lithological descriptions of drill core and morphological classification of the microdiamonds, indicate that the NW dyke consists of a single phase of kimberlite.
Specifically, the dyke is believed to be a continuous sheet dominated by hypabyssal (macrocrystic) kimberlite. Local areas occur in the dyke where an abundance of country rock fragments define the material as kimberlite breccia. Winspear says this variety of kimberlite is uncommon and generally thin, and that it normally occurs with thicker sections of hypabyssal kimberlite.
The microdiamond analysis, performed by Lakefield Research, grouped results on a 400-metre-square grid over the sample area. In each grid, normalized diamond counts were plotted in stones per tonne for all the micros that remained on a 0.3-mm-square mesh screen and passed through a 1.18-mm-square mesh screen.
Results indicate a slight but progressive increase of microdiamonds towards the northeastern portion of the sample area, and Winspear says this suggests there is a corresponding increase in grade of kimberlite relative to the results obtained in pits 3 and 4. The two bulk-sample pits are in the southwestern portion of the sample grid.
Winspear continues to study the results and intends to compare them to the geological model that has been developed for the NW dyke. The evaluation should enable the company to determine a grade for the 18 million tonnes of kimberlite and kimberlite breccia identified to date.
Meanwhile, WWW International Diamond Consultants has released its final diamond evaluation report for the project. As previously reported (T.N.M., July 26-Aug. 2/99), Winspear recovered 10,708 carats from processing 5,985.7 dry tonnes of kimberlite. The diamonds were determined to have an average value of US$104.96 per carat.
The final report states that 25.1% of the total carats recovered were larger than 0.9 carat and represented 72.4% of the total value of the parcel. The report also indicated that 4.06% of the diamonds recovered were larger than 4.8 carats and represented 21.9% of the value of the parcel. This demonstrates that a substantial portion of the diamond value hosted in the NW dyke is contained within diamonds larger than 0.9 carat, Winspear says.
The company adds that environmental and geotechnical programs are continuing.
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