In 2004, as part of a major campaign to recover at least 300 carats of diamonds for valuation purposes, the partners undertook a comprehensive bulk-sampling and drilling program on the Renard 2, 3, 4 and 65 bodies. The four pipes form a higher-grade core area at the southern end of a 2-km-long cluster of nine diamond-bearing bodies, in the south-central part of the property. Six of the nine bodies occupy an area measuring only half a square kilometre.
Ashton and Soquem collected a 635-tonne sample from the four kimberlitic pipes. Of the 415 tonnes of kimberlite processed to date, 282 carats of diamonds exceeding 1.18 mm in size have been recovered. Twelve of the diamonds weigh more than 1 carat apiece, including six stones that exceed 2 carats apiece.
“We expect to have between 300 and 400 carats of diamonds for evaluation,” says Brooke Clements, Ashton’s vice-president of exploration. Results are pending for about 220 tonnes of the remaining bulk sample, including 150 tonnes from Renard 2, fifty tonnes from Renard 4, and 20 tonnes from Renard 65.
“We should have those results by the end of February,” Clements says. “Getting a preliminary idea for diamond values is critical for gauging the economic potential of the project.”
In the most recent batch of results, 146 tonnes of sample collected by reverse-circulation (RC) drilling from Renard 3 delivered 184 carats of diamonds for an estimated grade of 1.26 carats per tonne. The sample batch held the largest diamond recovered thus far from the Renard cluster: a 4.3-carat stone described as a clear, colourless octahedral crystal. Until now, the biggest stone recovered had been a 4-carat diamond (a clear octahedral) discovered last year embedded in a piece of drill core from the Renard 65 body.
The Renard 3 sample batch contained 10 diamonds weighing more than 1 carat apiece, with five stones greater than 2 carats, including a clear, colourless tetrahexahedroidal shape weighing 2.7 carats, and a clear and colourless 2.29-carat octahedral.
Renard 3 measures 145 by 25 metres. The 146-tonne sample was collected by drilling six large-diameter (27-cm) RC holes to an average depth of 175 metres. Five of the six holes bottomed in kimberlitic material. An additional smaller sample of 8.6 tonnes collected during the 2004 summer from the drilling of eight core holes has yielded a previously reported grade of 0.68 carat per tonne, based on the recovery of 5.89 carats of diamonds.
The latest results are much more in line with those returned by earlier, mini-bulk drill core samples taken in 2002 and 2003. Renard 2 had originally shown grades of 1.53 carats per tonne based on the recovery of 7.81 carats exceeding a 1.18-mm cutoff in a 2003 sample of 5.1 tonnes, whereas a 2002 mini-bulk sample of 4.9 tonnes returned 6.54 carats of diamonds greater than a 0.85-mm cutoff, for an implied grade of 1.34 carats per tonne. The largest diamonds in each of these early sample batches were a 1.82-carat stone described as a colourless octahedral with uneven surface characteristics and a 0.73-carat colourless composite crystal.
So far, 165 tonnes of processed material from Renard 3 have yielded 204 carats, giving an implied diamond grade of 1.24 carats per tonne. A detailed look at the cumulative bulk-sampling results to date for each of the Renard 2, 3, 4 and 65 bodies is provided in the accompanying table.
During the 2004 bulk-sample drilling campaign, Ashton used both core and large-diameter RC drilling to sample the four Renard bodies. Vertical core holes were drilled on a 20-metre grid pattern to an average depth of 200 metres, providing more than 1 tonne of sample from each hole. The core drilling provided geological control for the positioning of the larger-diameter RC holes, which generated about 15-20 tonnes of sample for a 150-metre-long hole.
The Foxtrot property covers almost 2,000 sq. km in the Otish Mountains region, 400 km northeast of the mining and forestry town of Chibougamau. The project is a 50-50 joint venture between Ashton and Soquem, with the former as operator.
In 2004, the partners drilled 59 core holes (72 tonnes) and 23 large-diameter RC holes (567 tonnes) during the bulk-sampling campaign on Renard 2, 3, 4 and 65. In total, 163 holes have been drilled into these four bodies.
“This information is going to allow us to do a tonnage calculation,” says Clements.
The Renard 2, 3, 4 and 65 bodies cover a cumulative surface area of 3.4 hectares. The resulting valuation of the parcel of 300-400 carats of diamonds will provide the joint venture with a preliminary glimpse of the economic potential for the Renard bodies. Typically, it takes a parcel of at least 3,000 carats of diamonds to provide a valuation deemed representative enough for a bankable feasibility study.
“Once we get the valuation, we are going to make a decision on whether or not to proceed with prefeasibility-type work, which could include more resource definition drilling and the collection of a larger bulk-sample,” explains Clements. “Through it all, we are going to be aggressively exploring in an effort to find more tonnage away from the Renard cluster.”
The joint venture is carrying out more definition drilling on Renard 2 and 3, as well as on the northern end of Renard 4. The northernmost holes into the Renard 2 and 3 bodies have intersected kimberlite outside of the projected boundaries. At Renard 4, most of the work has been focused on the southern half of the body, but during the summer, Ashton exposed an outcrop at the northern edge. A 1.8-tonne sample from that surface exposure yielded 3.1 carats of diamonds for a grade of 1.72 carats per tonne, compared with an overall grade of 0.45 carat per tonne based on the total 123-tonne bulk sample. “It’s obvious we have to do more work on the northern end of the body,” says Clements.
The core area of the property has been explored using airborne geophysical surveys. More than 19,000 line km of additional magnetic and electromagnetic surveys will target the remainder of the Foxtrot property. The resulting airborne data will complement the results of a property-wide, heavy mineral sampling program in 2004.
The joint-venture partners plan to drill 10 targets that are either associated with the Lynx anomaly, 2 km west of the Renard cluster, or are found elsewhere on the Foxtrot property.
Lynx is a strong anomalous area of kimberlite indicator minerals, with associated kimberlite float, containing a “healthy population of G10, or diamond-friendly garnets.” One till sample, taken from the Lynx area in 2000, contained a staggering 9,000-10,000 kimberlite indicator mineral grains and was responsible for triggering the staking of the Foxtrot property, beating out the likes of
This one sample returned a full suite of indicator minerals, including pyrope garnets, ilmenites, chrome diopsides, chromites, and, most importantly, diamonds. The joint venture has since found kimberlitic boulders and cobbles at more than 100 sites along a 4-km strike. The strongest portion of the Lynx anomalous area terminates near a linear topographic feature that strikes 345 and is believed to be the source of the kimberlite boulders.
In the fall of 2003, while drilling a broad, weak geophysical anomaly in one area at the head of the Lynx indicator mineral train, the joint-venture partners intersected a 4-to-5-metre-wide zone of narrow hypabyssal kimberlite dykes, the largest being 1 metre thick.
In addition, abundant kimberlite float measuring up to 2 metres in diameter was found on surface 100 metres down-ice of the disc
overy holes. A 3.9-tonne sample of the boulders returned 4.63 carats of diamonds larger than 0.85 mm, giving an estimated diamond content of 1.2 carats per tonne. The two largest diamonds are a colourless composite crystal weighing 0.96 carat and 0.28-carat pale-brown octahedral.
Ashton has since tested the Lynx structure with 17 holes and hit kimberlite in 15 of the holes, confirming the presence of a continuous or semi-continuous dyke system over a distance of 3.7 km. At one of the drill sites, Ashton intercepted solid kimberlitic intercepts of 3.7, 1.9 and 2.2 metres in three separate holes, defining a sill-like feature dipping 15 to the east. The dips are highly variable along the Lynx structure. Ashton is awaiting microdiamond results from the drill core, as well as results from a 5.6-tonne boulder sample from the northern end of Lynx and a 4.9-tonne sample collected from boulders at the southern end.
Clements notes that there are 20 unexplained geophysical anomalies along the Lynx trend, several of which will be drilled.
Outside of Lynx and Renard, Ashton has defined five distinct indicator mineral anomalies, with associated kimberlite float. Pebble- and cobble-size kimberlitic boulders have been discovered at three new sites as far away as 15 km from the Renard cluster.
In addition to the work at Foxtrot, further exploration is planned for the 150-sq.-km Monts Otish property, 80 km southeast of Foxtrot. “We have several reasonable geophysical anomalies and plan to investigate a few of these by drilling this year,” says Clements. Monts Otish was originally staked in 2003 on the basis of favourable regional heavy mineral sampling results.
Other junior companies active in the Otish Mountains region include Majescor Resources, which is exploring on several fronts through joint-venture agreements with
On the neighbouring Portage project, which sits down-ice of both the Renard cluster and Lynx kimberlitic dyke system, Majescor carried out a grid-patterned sampling campaign in 2004. In total, 1,336 samples were collected on fence lines positioned perpendicular to the known glacial movement. The highest count from one individual sample was 100 kimberlite indicator mineral grains. In follow-up prospecting, kimberlitic float up to a half-metre in diameter was discovered over a 75-metre area, 175 metres up-ice from the anomalous till sample.
A 136-kg sample of the kimberlitic float returned 32 microdiamonds. The two largest stones, measuring 0.9 by 0.7 by 0.4 mm and 0.88 by 0.64 by 0.38 mm, were captured on the +0.425-mm square mesh sieve. Further till sampling suggests the head of the indicator mineral dispersion train is confined to a 500-by-500-metre area.
As a result of investing $500,000 in a private placement financing of Majescor last year, Stornoway has the right to acquire a 51% interest in the Portage project once Majescor has spent $1 million on exploration.
The 33 Carats project covers four non-contiguous property blocks totalling 918 sq. km. The properties were originally map-staked in the summer of 2001 on the periphery of Ashton and Majescor’s core holdings in the Otish Mountains. The northern and southern property blocks are within 20 km of the Renard discoveries.
Reconnaissance till sampling by Dios revealed favourable G10 pyrope garnets, picroilmenites, and high-magnesium olivines in selected samples. In 2003, De Beers funded airborne magnetic surveys totalling 11,761 line km, with follow-up ground investigations on 14 targeted areas. More than 1,100 heavy mineral samples have been collected.
Dios reports that till samples from one target area contained G10 pyropes exhibiting favourable diamond inclusion chemistry. A highly touted drilling program was planned for last fall but has been rescheduled to begin in the week ahead. Dios has picked up additional ground covering 503 sq. km along the Eastmain and Fire Rivers in the Otish Mountains, as well as a new project, Artaud, based on promising till sampling results 80 km north of Chibougamau in the De Maures River area.
In the Tichegami area, 90 km south of Foxtrot,