After enjoying success in the Northwest Territories, some members of the original Snap Lake discovery team formed
Nordic’s main focus is the advanced Kuopio-Kaavi diamond project, in southeastern Finland, 350 km northeast of Helsinki. The project area includes the Kuopio-Kaavi diamond field, on the Karelian Craton, which is also host to the notable diamond deposits in the Archangelsk diamond field of Russia. Two small clusters of kimberlite pipes were discovered by Ashton Mining of Australia between 1986 and 1998.
Nordic’s predecessor company, Poplar Resources, acquired the Kuopio-Kaavi project in April 2002 after the previous operator failed to define suitable structures. Nordic now holds 100% title to 18 of 20 Group I kimberlites in the region and has initiated a comprehensive, $1.5-million exploration program on the property. Results from the first phase of drilling are now in hand.
Previous work at Kuopio-Kaavi had established that 15 of the kimberlites currently held by Nordic contain diamonds. Mini-bulk samples collected from Kimberlites 21 and 12 by the previous operator returned grades of 26.6 carats per 100 tonnes and 17.1 carats per 100 tonnes, respectively, with a 1.126-carat diamond being recovered from Kimberlite 21.
Nordic’s interpretation of the Ashton drilling data is that the Kuopio-Kaavi geology is unconventional and may share some structural similarities with that of the Snap Lake project, which is being developed into a mine by
Walter Melnyk, Nordic’s president, and two of Nordic’s consultants were instrumental in the Snap Lake discovery in 1996. At the time, they were employees and consultants for Winspear Resources, which subsequently sold the property to De Beers in 2000 for US$310 million. Melnyk was Snap Lake’s project manager for Winspear, and Nordic consultant John MacDonald was Winspear’s vice-president of exploration. Nordic consultant Nicolai Pokhilenko was also a key player in this discovery.
A reinterpretation of existing technical data suggests that Kimberlite 21 may possess substantial tonnage potential and a “large-stone” population. Furthermore, the data suggest that this body is not a conventional, vertical “carrot-shaped” pipe typical of most kimberlites but rather an irregular, inclined dyke structure. It trends east-west with a drill-indicated strike length of 240 metres and is open in both directions. The initial phase of drilling is trying to determine the structure of the kimberlite system, provide geological insight into phase complexities, and establish micro-macro diamond distribution.
Positive results
Nordic recently received positive results from its drill program and analysis of Kimberlite 12 and 21. Kimberlite 21 was tested by six holes totalling 715 metres. Based on all of the drill hole data, including the shallow holes drilled by the previous operator and the deeper holes drilled by Nordic, Kimberlite 21 is now thought to consist of two moderately plunging pipe-like bodies occupying a major east-west structure.
Drill hole K21-04-01 was drilled in the western portion of the kimberlite body and intersected 45.4 metres of kimberlite. The assumed true thickness is approximately 33 metres. Drill hole K21-04-02 was drilled 100 metres east of the first hole and intersected 102.6 metres of kimberlite. The assumed true thickness is 80 metres. K21-04-03, the easternmost hole, intersected 1.2 metres of hypabyssal kimberlite at depth. Drill hole K21-04-05, which is central to the kimberlite body, also intersected a narrow hypabyssal kimberlite dyke at depth.
As a result, Kimberlite 21 has now been defined over a strike distance of 215 metres, with kimberlite intersected in each of the six drill holes. The drilling has provided sufficient data to evaluate the target and underlying system and enable Nordic to gain a clearer understanding of the kimberlite emplacement mechanism for the area.
Kimberlite 12 was tested with two drill holes. Of particular significance is the intersection of 57 metres of hypabyssal kimberlite in the second hole. Drill hole KL-04-02 intersected 70.3 metres of kimberlite (the top 13 metres of the section consisted of tuffistic kimberlite breccia) and was stopped in kimberlite, owing to the limited capacity of the drill rig. The first hole, K12-04-01, tested the western extremity of the body and intersected 57.4 metres of tuffistic kimberlite breccia and bottomed in granitoids.
This drilling on Kimberlite 12 defined a minimum strike length of 160 metres and a width of at least 57 metres and perhaps greater than 70 metres. Compilation of the previous operator’s data suggest that this kimberlite is a moderately dipping dyke-like body striking east-west and dipping in a southerly direction. The body is open to the east. Kimberlite 12, situated 1.5 km south of Kimberlite 21, is close to the shore of a shallow lake, with the major part of the body lying below the lake. The previous operator reported a grade of 17.1 carats per 100 tonnes from the upper kimberlite breccia but did not fully evaluate or report grades on the hypabyssal kimberlite.
Analysis
Core samples from the two kimberlites were submitted to SGS Lakefield Research for diamond analysis using the standard caustic dissolution method with collection of the residue on a 150-mesh screen. A 287.72-kg sample from Kimberlite 21 garnered 264 diamonds, whereas a 156.36-kg sample from Kimberlite 12 yielded 122 diamonds.
The three largest stones from Kimberlite 21 had the following attributes: stone 1 was 1.2 by 0.77 by 0.69 mm, white, transparent, and fragmented with an octahedral surface; stone 2 was 0.94 by 0.8 by 0.54 mm, white, transparent and fragmented; and stone 3 was 1.08 by 0.86 by 0.69 mm, brown, translucent, fragmented, and with crystal faces. Almost 80% of the stones were white; the remainder were off-white, yellow, and brown. An estimated 91% of the diamonds were transparent, and 53% were fragments. The estimated degree of preservation is 85-99%.
The three largest stones from Kimberlite 12 had the following attributes: stone 1 was 1.2 by 0.88 by 0.22 mm, white, transparent and fragmented with no crystal faces; stone 2 was 0.8 by 0.68 by 0.51 mm, white, transparent and octahedral in shape; stone 3 was 0.83 by 0.6 by 0.43 mm, off-white, transparent and fragmented, with some crystal faces. In addition, visual analysis of all diamonds from this sample indicated that 93% of the stones were white, 99% were transparent, and 42% were fragmented. The estimated degree of preservation was 85-99%, and diamond crystals were primarily octahedral, though several cubic crystals and macles were observed.
The company will study the microdiamond population to assess the stone size distribution in both kimberlitic bodies, and thereby determine the potential for large-stone populations. Further work on these two kimberlitic bodies will be contingent on results from the microdiamond studies.
A third target, Kimberlite 17, will be tested at a later date, when a larger drill rig becomes available. Kimberlite 17 is a lake target, and ice conditions have been treacherous this year in central Finland.
This summer, heavy mineral sampling will try to identify new kimberlites. At present, geological, geophysical and geochemical data are being compiled in an attempt to identify prospective areas for examination.
— The author is Toronto-based geologist and freelance writer, as well as a frequent contributor to Canadian Mining Journal.
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