Undiscovered mafic-ultramafic rock-hosted chromium resources in Finland

Chromium resources in undiscovered podiform and stratiform chromite deposits were estimated down to the depth of one kilometre in the bedrock of Finland using the three-part quantitative assessment method. Sixteen permissive tracts were delineated for stratiform and two tracts for podiform deposits. The tracts cover altogether 7430 km2, which is two per cent of the total land area of Finland. An existing USGS minor podiform chromite grade tonnage model was used to assess the undiscovered podiform resources in Finland. For stratiform chromite, a separate deposit volume model for each permissive tract and a general model of chromium content per unit volume were used. The estimated mean numbers of undiscovered stratiform and podiform chromite deposits in Finland are 9 and 23, respectively. The undiscovered stratiform and podiform chromite deposits are estimated to contain, at 50 % probability, at least 350 Mt and 7600 t chromium, respectively. The assessment results indicate that at least 92 % of the remaining chromium endowment within the uppermost 1 km of the Finnish bedrock is in poorly explored or entirely unknown stratiform deposits. Practically all of the undiscovered resources are located in stratiform deposits in layered intrusions in northern Finland.