The Kuusamo belt contains several epigenetic-hydrothermal gold deposits with significant enrichments of Co and other base metals. Among them, the most significant is the Juomasuo deposit, which consists of one major mineralized zone and several smaller adjacent sulphidized zones. The total mineral resource estimate for the Juomasuo deposit is 2.37 million tonnes grading at 4.6 g/t Au and 0.13 wt% Co and an additional 5.04 million tonnes of Co resources without Au grading at 0.12 wt% Co.
The host rocks of the Juomasuo deposit are characterised by strong albitisation but the mineralized zones also contain quartz, chlorite, biotite, sericite, carbonate, amphibole and talc in addition to albite. The most abundant sulphide is pyrrhotite followed by pyrite and lesser chalcopyrite. Cobaltite can be found in the Co-rich parts of the ore as inclusions in pyrrhotite and sometimes in pyrite. Cobaltian pentlandite is also present mainly as exsolutions in pyrrhotite. Molybdenite, rutile, magnetite, native Au and tellurides (altaite, tellurobismuthite and melonite) are noteworthy accessories in the deposit.