In total 552 nickel-bearing sulfide deposits and occurrences in Finland have been examined and 254 of them have been selected for more detailed classification. In age they range from Late Archean to Middle Proterozoic (Subjotnian), of which economically the most significant are the Early Proterozoic Svecofennian deposits.

The deposits have been subdivided into 62 nickel-bearing metallogenic areas according to their type, age and spatial relations:

1. Late Archean and related deposits in northern and eastern Finland (2900-2500 Ma): Ruossakero Zone, central Lapland zones, other areas in northern Finland, and Kuhmo Belt.

2. Deposits in Early Proterozoic layered intrusions (2440 Ma).

3. Deposits within the Karelian formations (2070-1900 Ma): Vuonos, Lahnaslampi and Talvivaara zones.

4. Deposits within the Svecofennian Domain or its marginal zone (1900-1860 Ma): Kotalahti Belt (including Hitura, Kotalahti and Laukunkangas zones), zones and deposits to the northeast of the Kotalahti Belt, zones and deposits to the southwest of the Kotalahti Belt, deposits within the Sulkava area, Telkkälä Belt, deposits in western Finland, Vammala Belt (including Pori and Vammala zones), zones and deposits to the east of the Vammala Belt, and zones and deposits to the southwest of the Vammala Belt.

5. Deposits in Subjotnian diabases (c. 1650 Ma).

Grade and tonnage models for nickel-bearing deposits show that 10% of the 164 Svecofennian deposits have an average grade greater than 0.80% Ni and 0.40% Cu, or a size greater than 0.52 Mt of ore. At the 10% level the deposits in the Kola-Karelian Domain, hosted by komatiites, layered intrusions and Karelian formations have an average grade greater than 0.50% Ni, 0.30% Ni and 0.33% Ni, but varying grades of 0.13% Cu, 0.88% Cu and 0.30% Cu, and a size of 0.5 Mt, 55 Mt and 30 Mt respectively. At the 50% level the Kotalahti and Vammala nickel belts show an almost similar distribution of nickel and copper grades, but their average sizes are different. However, only 10% of these belts have an average grade greater than 1.06% Ni and 0.75% Ni, and 0.37% Cu and 0.47% Cu, or a size greater than 3.1 Mt and 1.0 Mt respectively.

Total geological in situ resources of Finnish nickel deposits have been estimated to be some 950 Mt with an average grade of 0.39% Ni and 0.29% Cu, which could be equivalent to a metal content of some 2.6 Mt nickel and 2.5 Mt copper. Between 1941-1994, the ore output of all nickel mines in Finland was about 42.3 Mt, at an average grade of 0.61% Ni and 0.25% Cu, which is calculated to be equivalent of some 260 300 t of nickel and 103 800 t of copper.

Based on the distribution of in situ ore resources and known ore deposits it is apparent that the overwhelming nickel potential is in the Svecofennian area, within the Kotalahti Belt and within the Vammala Belt. Economic ore deposits could also be found among the layered intrusions, whereas the Archean deposits are expected to contain only modest amounts of nickel. Current exploration in Finland could also reveal new types of economic nickel deposits.

Geological Survey of Finland
Betonimiehenkuja 4
FIN-02150 ESPOO
FINLAND

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