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Potentially economic grades are evident in 67 of the 98 infill and stepout holes for which assays are available. The holes, representing 28,515 metres in all, were aimed at three targets: a brecciated gabbro on the western and southern flanks of the producing Roby zone; a high-grade pyroxenite below the current pit, at between 244 and 396 metres; and a gabbronorite unit extending downdip from the North Roby zone.
Most of the significant intersections came from the brecciated gabbro, though the highest grades came from the pyroxenite. Results from the former include seven holes in which palladium values averaged between 1.65 and 3.5 grams per tonne, plus platinum, gold, copper and nickel values over core lengths ranging from 141 to 307 metres. Highlights from the pyroxenite unit include 9.36 grams palladium over 34.5 metres, 8.33 grams over 39 metres, and 7.23 grams over 69 metres.
North American Palladium is incorporating the results into an updated resource estimate, which will enable the company to decide whether or not to proceed with an expansion (T.N.M., May 31/99).
At last report, the Roby zone hosted proven and probable reserves of 7.08 million tonnes with a combined PGE grade of 4.22 grams.
Meanwhile,
Eleven holes tested the Jackie Rastall showing, a 500-metre-long zone from which up to 23.6 grams combined platinum-palladium-gold were obtained in chip samples. Two other holes, both of which failed to intersect any mineralization, were collared 150 metres to the west, where previous operators intersected 8 metres averaging 3.5% combined nickel-copper.
Combined platinum, palladium and gold values varied from less than 0.5 gram to 9.03 grams per tonne, with copper and nickel values generally ringing in at less than 1% but topping 3.37% and 1.67%, respectively. Mineralized intersections ranged from 3.22 to 16.16 metres in core-length and typically contained smaller, higher-grade cores.
Pacific North West says palladium is the principal PGE present, being between 3 and 7 times greater in abundance than platinum. Gold is the least abundant of the three precious metals noted, typically assaying less than 0.5 gram.
Mineralization is hosted by the Nipissing Diabase, where it contacts the surrounding sedimentary rocks. It has now been traced for 80 metres below surface, where it remains open.
Future drilling will target the depth and southern extensions of the Jackie Rastall zone, as well as try to pinpoint the nickel-copper prospect to the west. Pacific North West believes the two unsuccessful holes were too far east of the historical hole, as their diabase-sediment contacts fail to line up.
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