Winspear, Aber expand Camsell Lake’s potential

The final five holes of the fall drilling program have expanded the tonnage potential of the NW Snap Lake dyke at the Camsell Lake property in the Northwest Territories.

The drilling has been suspended in anticipation of freeze-up conditions.

Camsell Lake lies 220 km northeast of Yellowknife and 110 km south of the Ekati diamond mine. Winspear Resources (WSP-V) is the project’s operator and holds a 67.76% interest, with Aber Resources (ABZ-T) holding the remainder.

The NW dyke subcrops on a peninsula that juts into the northwestern corner of Snap Lake. The kimberlite dyke dips gently eastward under the peninsula and extends beneath the lake. In the spring, Winspear collected a 199.7-tonne bulk sample from two surface pits set 235 metres apart. The bulk sample yielded a 228.9-carat parcel of diamonds (including 21 stones weighing more than 1 carat), with the highest carat values ever reported in the Northwest Territories.

The stones were determined to be worth an average of US$301.43 per carat and with an implied grade of 1.14 carats per tonne; this equates to a value of US$343.63 per tonne of kimberlite.

A scoping study prepared by Mineral Resource Development Inc. (MRDI), a division of H.A. Simons, estimated that a portion of the NW dyke that underlies a peninsula jutting into the northwestern corner of Snap Lake contains a resource of 1.3 million tonnes. Details of that scoping study were released in early October.

The estimate is based on a 65-hole grid drilling program completed in the summer and fall of this year, and on 13 holes completed in 1997. The area drilled measures 850 metres along strike and between 200 and 400 metres wide. The main dyke averages a thickness of 2.6 metres but splits locally into two dykes separated by up to 2 metres of country rock.

Since that time, an additional five widely spaced holes were drilled to determine if the NW dyke continues northward on the other side of a crosscutting fault and to test the downdip extent of the dyke. The dyke had previously been intersected in limited, widely spaced drilling beneath Snap Lake, 1,800 metres east of a subcrop on the NW peninsula.

Three vertical holes were drilled on the lake’s northern shore, and all intersected kimberlite characteristic of the NW dyke over potentially minable widths. The first hole, CL98-15, was collared about 200 metres north of the NW peninsula and roughly 500 metres downdip from the projected subcrop, intersecting 2.8 metres of kimberlite material at a depth of 98.7 metres.

The second hole, CL98-16, was drilled a further 150 metres to the north and 450 metres east of the first hole, which equates to about 1,000 metres east of the projected subcrop. The hole encountered two intervals of kimberlite measuring 2 and 2.1 metres thick at a depth of 212 and 232 metres, respectively.

The third hole, CL98-19, was collared 300 metres north and 100 metres east of the first hole, returning a 2.6-metre interval of hypabyssal kimberlite hosted in granitic rock.

Two deep holes were drilled from islands near the eastern shore to test the downdip extent of the NW dyke. Hole CL98-17 was collared 300 metres north and 400 metres east of an earlier 1998 winter hole, CL98-13, which had intersected 1.2 metres of kimberlite some 1,800 metres east of the projected subcrop. Hole 17 encountered a 2.5-metre intersection of kimberlite typical of the NW dyke at a depth of 478 metres.

Winspear reports that this intersection occurs about 150 metres below the dyke’s projected depth and either reflects a change in attitude or a separate segment of the NW dyke. The hangingwall is marked by significant alteration of the granitic host rocks, while the footwall is relatively unaltered.

The second deep hole, CL98-18, was drilled 160 metres south and 350 metres east of hole 13. It was completed to a depth of 334 metres but only intercepted a 0.15-metre interval of kimberlite at a depth of 264 metres. Although this hole tested the NW dyke as projected from hole 13, Winspear believes it may not have continued deep enough to test the projection of the deeper kimberlite intersected in hole 17.

These five holes have expanded the strike of the NW dyke to 1,350 metres and the downdip potential to 2,200 metres east of the subcropping dyke. The eastern downdip margin, however, is defined only by holes CL98-13 and CL98-17, which indicate a minimum strike length of 350 metres.

Winspear believes there may be significant kimberlite tonnage potential underlying the northern shore, where there was no previous indication of kimberlite from surface sampling and prospecting.

In the meantime, a 500-kg sample of the NW dyke, representative of the bulk sample taken in the spring, is undergoing microdiamond analysis by Lakefield Research, as are the numerous kimberlite intersections from spring and summer drilling. Results will be reported as they are received over the coming months.

The microdiamond results will add to the geostatistical database on the dyke’s microdiamond distribution that is being established for purposes of grade prediction.

An aggressive delineation drilling program is planned for early 1999; the work will focus on the portion of the NW dyke that extends under Snap Lake. In addition, it is likely that the partners will take a further 5,000-to-10,000-tonne bulk sample of the NW dyke to verify diamond values.