Ashton's Otish hunt gets a promotable boost
2005-03-24 14:26 ET - Street Wire
by Will Purcell
The Lynx dike system offered new encouragement for Ashton Mining of Canada Inc., with a toutable grade and the largest Otish Mountains diamond yet. The Lynx system first proved promotable early last year, when a first batch of kimberlitic float delivered one of Ashton's best mini-bulk grades from its Foxtrot play so far. The company poked several holes into the substantial dike complex since then, but speculative interest in the story hinged on the outcome of two more mini-bulk tests that the company scooped up last year. Based on those results, Lynx could be a busy place this year.
The latest Lynx tallies
There was a marked difference in the latest two samples, although much of that variance might be explained away as the result of a stroke of luck. The best sample came from boulders scooped up from a site dubbed Lynx South. About 4.6 tonnes of rock produced 11.8 carats of diamonds that were large enough to remain on a 1.18-millimetre sieve. That works out to a sparkling grade of 2.56 carats per tonne, by far the best of Ashton's tests so far. The Lynx South sample came from a site about 1.5 kilometres to the south of where Ashton gathered its first batch of Lynx boulders early last year.
A single large diamond helped inflate the value. Ashton recovered a 5.66-carat pale brown octahedral diamond in that sample, along with a 1.17-carat pale brown composite crystal. The two diamonds account for nearly 60 per cent of the entire parcel. The largest stone does seem a bit of a fluke at this stage, but the 1.17-carat diamond offers support that Lynx could be a prolific producer of large diamonds.
That was not the case at Lynx North. Ashton processed 5.66 tonnes of kimberlite boulders from a region about one kilometre north of the site of its first mini-bulk test and roughly 2.5 kilometres north of the Lynx South boulders. The Lynx North kimberlite produced just 2.68 carats of diamonds larger than a 1.18-millimetre screen. That worked out to a grade of 0.47 carat per tonne. That was well below the result at Lynx South, but still a promising outcome.
If Ashton got lucky at Lynx South, the company was decidedly unlucky with the northern batch of kimberlitic float. Ashton's largest diamond weighed just 0.27 carat. Had the northern ample produced just two one-carat diamonds, with a total weight of three carats, the grade of the Lynx North sample would swell to about one carat per tonne. As a result, it seems far too early to suggest that the northern rock has a lower grade than the material from the southern site.
The first Lynx tests
The Lynx story began just over a year ago, when Ashton recovered 4.63 carats from 3.87 tonnes of kimberlite boulders that it found just west of its Renard kimberlite cluster. That tally pointed to a grade of about 1.2 carats per tonne. At the time, that value ranked behind just Renard-3, placing it second among all of Ashton's kimberlite finds in the Otish district.
Ashton used a 0.85-millimetre cut-off for that Lynx test, as it did for all of its early Renard mini-bulk samples. That smaller sieve size would collect added quantities of smaller diamonds and inflate the grade of the sample somewhat. In some deposits with few larger stones, the smaller cut-off could add up to 20 per cent to the sample grade.
The grade boost at Lynx was likely smaller than that, as there were some larger stones in the mix. The largest diamond weighed 0.96 carat and a second stone weighed 0.28 carat. The finds offered hope that the source of the Lynx boulders had a favourable diamond size distribution curve. A coarse curve would limit the grade contribution in the smallest sieves, compared with a deposit with a less favourable distribution.
The rock did not appear to originate from its Renard pipes, and the company soon found a bedrock source for the material. As well, Ashton scooped up boulders from other sites, sending the rock for microdiamond recovery. Those samples offered encouragement as well. In all, 316 kilograms of material produced 883 diamonds larger than a 0.10-millimetre cut-off. That worked out to about 2,800 stones per tonne.
The haul included 184 diamonds large enough to sit on a 0.30-millimetre mesh, which was about 21 per cent of the entire parcel. As well, 68 of the diamonds sat on a 0.425-millimetre sieve, accounting for about 7.7 per cent of the parcel. Seven of the diamonds remained on a 0.85-millimetre screen and three of those were large enough to sit on a 1.18-millimetre sieve.
Most of that rock came from a site about 150 metres southwest of the first Lynx mini-bulk sample, but nearly 80 kilograms of the material originated from a spot roughly one kilometre to the north. That site is close to where Ashton collected its recent Lynx North mini-bulk sample. The rock contained 289 diamonds, or about 3,700 stones per tonne.
That rate was actually higher than what the 239 kilograms of rock from the main Lynx site produced. On the other hand, the size distribution of the diamonds from the 77 kilograms of northern kimberlite was slightly less favourable.
Diamonds large enough to sit on a 0.30-millimetre sieve accounted for 23 per cent of the stones in the main sample, while the proportion within the northern rock was 16 per cent. About 8 per cent of the main Lynx diamonds clung to a 0.425-millimetre screen, while the fraction within the northern material was 7 per cent. Based on those values, it is possible that the kimberlite in the northern region has a somewhat lower grade than the rock in the central part of Lynx.
The tiny size of the samples makes any such assumptions a risky proposition, as there could be any number of explanations for the differences. The difference could be the result of normal random statistical variation in small samples. As well, there could be different grades within different parallel dikes along the Lynx feature. There is no indication of precisely where the kimberlitic boulders came from at this stage.
In all, Ashton now has the diamonds from 14.2 tonnes of Lynx kimberlitic boulders. That material delivered 19.1 carats of diamonds, pointing to a grade of 1.35 carats per tonne. That figure now puts Lynx at the head of the Otish Mountains kimberlite pack, although the company has yet to actually process a mini-bulk test of the source material.
The system
Ashton began poking holes into the Lynx area in 2003 and the company has tested the feature with holes at 15 separate sites so far. The drilling spans a distance of about 3.7 kilometres, although Ashton thinks the system has a strike length of at least 4.5 kilometres.
Drilling produced kimberlite intersections ranging from a few centimetres, up to 3.7 metres. The latter occurrence was in the southernmost part of the Lynx system, which so far has produced the more encouraging drill hits. Twenty holes at 10 sites along a 900-metre span of Lynx South produced an average intersection of about 1.6 metres. Besides the 3.7-metre hit, there were six more intersections that topped the two-metre mark, with another seven that measured at least one metre in thickness. Six hits were less than one metre wide.
Ashton's drilling was more sporadic in the central and northern regions of Lynx. The company poked 11 holes at five sites, spanning a distance of just over two kilometres. The thickest hit measured 2.4 metres, in a hole near the site of the first mini-bulk test. The average intersection was about 1.2 metres, with four of the 11 holes producing hits measuring less than one metre wide.
It is far too soon to draw any meaningful conclusion, but the thickest parts of Lynx may lie in the central and southern parts of the system. The four most northerly of Ashton drill holes yielded an average intersection of just 0.7 metre, while the seven holes into the central regions resulted in an average thickness of about 1.5 metres. That would be a favourable result, if it turns out that the central and southern parts of Lynx do in fact have the better grades to go with the potentially thicker dikes.
The plan
Ashton should have its microdiamond recoveries from the core samples recovered during its busy 2004 drill program. The combined thickness of all 31 holes is just 44 metres, so the amount of kimberlite available for processing is limited. Nevertheless, the rock could provide confirmation of the diamond potential of the system in general, as well as offering some glimpses into potential variations along the body.
Ashton plans more geophysics along Lynx this year, along with a prospecting program. That work will try to find potentially wider zones within the dike system, and the company will undoubtedly drill several new holes into Lynx this year.
The Lynx project would get a good boost if Ashton's drill program produces a significantly wider region along the strike length of the complex dike system. As well, the discovery of a small pipe or blow along the dikes would improve the tonnage potential of the system. Lynx could still be an economic source of diamonds without such thicker zones, but mining a narrow dike system would result in significant dilution by country rock. As a result, the latest sample grades give the project a hefty lift.
Ashton's shares dipped below the $1 mark last fall, sinking to a low of 87 cents in mid-December as speculators became impatient with the company's Otish play. Some toutable grades from Renard-2 and Renard-3 brought renewed interest this year, and the stock recently poked above the $1.50 mark for a time.
Ashton gained 43 cents on Wednesday, closing at $1.78 on 1.4 million shares. |
