Given the interest in exploration for platinum group metals (PGMs) in northern Ontario and its long history of gold production, it is surprising that more explorers are not targeting projects in Finland.
The country’s shield geology, so similar to Canada’s, offers potential for gold and platinum-group mineralization and a few companies are now nibbling at the projects it offers. Moreover, it’s a rarity: a first-world country that likes mines.
The Arctic Platinum Partnership, a joint venture between
The geological feature of interest is the 125-km margin dividing Proterozoic volcanic and sedimentary rocks of the Svecofennide belt from older Archean gneisses to the south. Along the margin, a series of layered mafic intrusions hosts platinum-group showings. Two intrusions have seen the bulk of the work.
At the Penikat intrusion, about 130 km northwest of Oulu, Outokumpu drilled about 700 holes in the period before 1989 to define three “reef”-style layers in the gabbro complex.
The Penikat zones are true layered deposits on the pattern of Stillwater and the Bushveld, but the resources the partnership has so far defined have come from the Portimo complex, another 65 km to the northeast. There, two disseminated sulphide deposits, Ahmavaara and Konttijarvi, have been drilled off at the base of the Portimo intrusion or in Archean gneisses in its footwall.
The best-developed resource is at Konttijarvi, where the partnership has outlined 23.6 million tonnes, grading 0.43 gram platinum, 1.57 grams palladium and 0.11 gram gold per tonne, with credits of 0.09% nickel and 0.14% copper. About a third of the resource is in the measured and indicated categories.
At Ahmavaara, an inferred resource of 25.6 million tonnes grades 0.26 gram platinum, 1.25 grams palladium and 0.12 gram gold per tonne, plus 0.11% nickel and 0.24% copper.
Gold Fields, as operator, is preparing a prefeasibility “scoping study” based on the resources at Konttijarvi and Ahmavaara, which was to have been ready near year-end. At Penikat, a drilling campaign, which is scheduled to finish this month, will provide a resource figure down to a 500-metre depth. The partners are considering a central mill and possibly a smelter.
Farther east, within the Karelian Shield, North Atlantic Natural Resources, a Swedish-listed company in which
In July 2000, North Atlantic won a tender competition called by the Finnish industry ministry. Under its tender agreement, the company must meet prescribed exploration expenditures over three years; the deposit can then be bought outright by covering the survey’s expenses in bringing the project to market, with the government retaining a net smelter return.
North Atlantic has an 8,500-metre drilling program laid on for 2001, during which time it will test six prospects on the property. The most advanced is Lavotta, where the Geological Survey outlined a 3-million-tonne resource grading 0.25% copper and 0.21% nickel. At the time of the survey’s work, the interest was in base metals, so PGMs were not tested; North Atlantic believes the grades are likely to be comparable to those at other showings in the area — for example at the Musta prospect, immediately west of Lavotta.
There, the company has already drilled 14 holes covering a 1.5-km strike length of the intrusion’s marginal zone. North Atlantic’s drilling intersected several 6- to 20-metre-wide seams of disseminated sulphide mineralization with precious metal grades in the sub-gram range, plus copper and nickel credits.
Two other showings, Parjanoja, 5 km west of Musta, and Rusamo, 6 km west of Parjanoja, yielded drill intersections 15-25 metres long over strike lengths of about 1 km each. The average grade of the mineralized intersections at Parjanoja was 0.36% copper and 0.17% nickel; at Rusamo, it was 0.27% copper and 0.17% nickel. Again, no PGM data exist.
Another occurrence, Selkavaara, was trenched by the survey in the 1980s, and six of 20 trenches revealed mineralized zones with surface widths of 10-38 metres. Copper and nickel grades clustered around 0.3%, with gold, platinum and palladium grades in the 0.1-0.2-gram range. South Atlantic recently announced it is considering acquiring North Atlantic’s platinum-palladium properties, a move that might be tied to Boliden’s capital-management program.
Swedish-based
Suurikuusikko is in a north-striking shear in Proterozoic-aged basalts and metasediments, in an albitic alteration zone with pyrite and arsenopyrite. The mineralization averages 12 metres wide, with thinner secondary zones in the footwall and hangingwall of the shear, and the deposit has a strike length of close to 1 km.
Recent deeper holes tested the northern and southern ends of the zone. In the north, one hole intersected 7.4 metres of mineralization grading 3 grams per tonne, at a depth of about 270 metres.
In the south, one hole cut four relatively narrow mineralized zones with grades of 1.4 to 2.2 grams but indicated that the mineralized structure did not have the steep plunge that had earlier been assumed. A second hole, drilled at a more shallow angle, cut 78.8 metres that averaged 8.4 grams gold per tonne at a depth of about 250 metres.
The deposit has touchy metallurgy, owing to the arsenopyrite, but tests of a 3-stage recovery process, in which a sulphide concentrate is floated, then bio-oxidized, then cyanide leached, gave a total recovery of 86%. An environmental impact study is also under way.
Be the first to comment on "Finnish precious metal projects lure explorers"