Kaunisvaara Iron Ore Project is directly owned and operated by Kaunis Iron AB, which is wholly owned by Kaunis Holding AB. Kaunis Holding AB is owned by a group of Swedish investors, with no single shareholder holding 10% or more.
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Summary:
The Kaunisvaara mining district hosts several iron ore deposits, of which Tapuli and Sahavaara are the most economically important. These deposits belong to an elongated cluster of iron-rich skarn mineralisation and banded iron formations (BIF) occurring over north-eastern Norrbotten from Masugnsbyn to the Pajala area.
The Tapuli deposit is divided into two adjacent open pits (Central and North), each with distinct iron and sulphur grades. Mineralisation occurs as magnetite-rich skarn alteration associated with Karelian greenstones (c. 2.3–2.0 Ga) and Svecofennian sedimentary rocks (c. 2.0–1.8 Ga). Magnetite is the only ore mineral being mined.
KIAB's ambition is to expand the present mining operation to include the Sahavaara deposit, which already is covered by the current exploitation concession. Extensive exploration has recently been conducted in Sahavaara.
Tapuli Mineralisation
The mineralisation is comprised of a highly variable magnetite-rich skarn alteration which largely overprints the footwall dolomite (Baker et al., 2011). Mineralised zones appear as NE striking lenses and bands, dipping concordantly with the local stratigraphy 45–60° to the NW. The mineralisation continues from the central portion of the deposit, forming elongated extensions to the NE and SW with a total length of roughly 2 km . The thickness of the skarn alteration ranges between 20 and 250 m and correlates with the thickness of the dolomite. Generally, where the skarn alteration is thick the dolomite is thin and vice versa. Still, the combined thickness of the two units is consistently around 250 m throughout the deposit (Baker & Bonson, 2013). The extent of the mineralisation has been outlined by exploration drilling to a maximum of 300 m below the surface, so the vertical reach of the deposit is not fully constrained (Baker et al., 2011).
Three major types of skarn assemblages have been distinguished in the deposit: clinopyroxene-tremolite alteration, magnetite-actinolite alteration, and serpentine alteration (Bergman & Hellström, 2020; Baker & Bonson, 2013). Dishaw & Lepley (2021) suggested that the clinopyroxene-tremolite alteration predates the magnetite-actinolite counterpart, while the serpentinization represents the final alteration stage. The latter, thus, postdating the main mineralisation event. Nevertheless, magnetite-rich zones occur in all three major skarn assemblages and in the highest-grade portions of the deposit, serpentine is the dominant gangue mineral (Dishaw & Lepley, 2021). The protolith for the mineralisation has not been conclusively determined, but local zones of biotite- and albite-rich alteration in the skarn indicates that the protolith may have been an aluminium-rich silicate rock rather than dolomite (Dishaw & Lepley, 2021).
According to Dishaw & Lepley (2021), the average sulphur grade of the mineral resources amounts to 0.4% S. However, sulphides are unevenly distributed throughout the mineralisation and individual bench-scale samples from production drill holes in the mineralised zones occasionally contain up to 10% S. Pyrite and pyrrhotite are the main sulphide minerals along with minor chalcopyrite. Cu concentrations are generally low in the sulphide bearing zones but still contain a few hundreds of ppm (Dishaw & Lepley, 2021). Sulphur grades typically increase with depth and the highest concentrations are found within the lowermost layers near the footwall contact. Similarly, the pyrrhotite-pyrite ratio increases with proximity to the footwall and, particularly, close to the graphitic phyllite (Denisova, 2013). Closer to the hanging wall, pyrite appears to be the dominating sulphide, with pyrrhotite occurring only sporadically.