While following up on promising overburden kimberlite indicator mineral chemistry with auger-core drilling,
Using two auger drills, the partners had completed about 200 short vertical holes when the discovery was announced. Kimberlite was intersected at a depth of 7 metres carrying through to the end of the 12-metre-deep hole. The holes are positioned on grid lines oriented to discover the source of anomalous indicator minerals recovered previously from reconnaissance overburden sampling in an area with no magnetic high or low targets.
The kimberlite indicator minerals, including G10 garnets, chrome diopsides, eclogitic garnets and olivines, were found in 17 earlier samples. Many of the indicator minerals exhibited angular (near-source) morphologies and favourable diamond inclusion compositions. At least 10 of the grains were attached to fragments of kimberlite. A hand-panned concentrate of weathered kimberlite from the discovery hole contained abundant picroilmenite, as well as subordinate chromite, olivine and chrome diopside. A 35-kg sample of kimberlite was recovered from the discovery and is being shipped to C.F. Mineral Research laboratory in Kelowna, B.C., for microdiamond and indicator mineral analysis.
Interests in the Attawapiskat joint venture are held 52.5% by Metalex, 17.5% by Arctic Star, and 20% by Big Red Diamond, a privately owned Timmins-based company. The remaining 10% is a carried interest retained by Kel-Ex Development, the operator of the joint venture. Kel-Ex is wholly owned by Charles Fipke, the chairman and a director of Metalex. Fipke is also a principal of C.F. Mineral Research.
The Attawapiskat joint venture covers 348 sq. km of mineral claims, about 90 km west of the coastal community of Attawapiskat. The claim package was originally staked in the spring of 2001 by Kel-Ex and Big Red to cover magnetic anomalies in the general area of a north-northwest-trending cluster of 19 known diamondiferous kimberlite pipes. De Beers discovered 16 of these bodies, including Victor, as a result of drilling in 1988 and 1989. More than 100 kg of core from each of the discoveries was initially analyzed for microdiamonds, and all but one proved to be diamond-bearing.
Two additional small kimberlites, known as MacFayden 1 and 2, were discovered in 1994 by
A vertical hole drilled into MacFayden 2, roughly 400 metres southwest of MacFayden 1, intersected 88 metres of kimberlite beneath 37.5 metres of overburden and 59 metres of limestone. Three micros were recovered from an unknown amount of drill core.
In February 2001,
The Victor deposit consists of two adjacent pipes, Victor South and Victor North, which coalesce at surface and cover an area measuring 16 hectares (39.5 acres).
The geology of the multi-phase Victor kimberlite is complex and highly variable in diamond grade. Bulk-sampling in the winters of 2000 and 2001 entailed the collection of 10,042 tonnes of kimberlite surface trenching and the drilling of 37 large-diameter reverse-circulation holes. In total, 3,788 carats of diamonds were recovered, representing an overall grade 0.38 carat per tonne (or 37.7 carats per 100 tonnes). This parcel was valued at more than $1.5 million, giving an average value of $405 per carat.
De Beers has established a revenue value of $94 per tonne for Victor, with a minable open-pit resource of 25 million tonnes of kimberlite to a depth of 200 metres and the potential for an additional 3 million tonnes.
The Victor project is within 10 km of any of the nearest Attawapiskat joint-venture property claims, which extend up to 82 km southeast of Victor. The Attawapiskat and Atikameg Rivers occur in the central and southern parts of the ground jointly held by Metalex and Arctic Star.
After staking the initial claim package, Kel-Ex and Big Red Diamond completed an orientation survey down-ice and down-stream from some of the known diamond-bearing kimberlites in the Attawapiskat kimberlite field. The orientation survey detected small quantities of diamond indicator mineral grains in clay-rich glacial sediments. In contrast, higher amounts of indicator mineral grains were found in washed alluvium stream-sediments.
Magnesium present
As a consequence, personnel of Big Red Diamond, initially accompanied by Fipke, collected 14 regional stream-sediment samples within the projected down-ice dispersion of their claims in the fall of 2001. The samples were sent to C.F. Mineral Research for analysis. Favourable kimberlitic indicator minerals were recovered in all but one of the 14 samples. Three of the samples contained five grains that were classified as diamond inclusion-type minerals, including distinct compositions of olivine, clinopyroxene and a G10 pyrope. A number of picroilmenites recovered from four samples contained a moderate to high amount of magnesium, suggesting moderate diamond preservation potential.
After bringing Metalex and Arctic Star into the deal, two high-resolution aeromagnetic surveys were flown over the project area. This past May, the partners drilled three deeply buried geophysical targets without any supporting indicator mineral chemistry, 20-45 km from the Victor project. Two of the holes intersected meta-kimberlite that was described as “macroscopically similar to diamond-bearing rock meta-kimberlite rock from elsewhere in Ontario.” The new discoveries contained varying amounts of pyrope garnet, eclogitic garnet, picroilmenite and chrome diopside, but no diamonds. Microprobe analysis of the indicator minerals indicated they did not have favourable diamond inclusion chemistry.
Auger overburden sampling has been carried out to screen airborne targets, with the objective of identifying those having diamond potential. Of the 331 auger samples collected from the vicinity of some 50 magnetic targets, 159 contained minor to strongly anomalous kimberlite indicator minerals.
In addition to further claim staking, the joint venture has carried out ground magnetic surveys on 37 targets. The auger-core definition drilling, which began this fall and resulted in the new kimberlite discovery, is continuing. A ground geophysical orientation survey is being done over the discovery to determine what geophysical methods work best, since airborne magnetics failed to detect the kimberlite.
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