Cobalt enrichment in some ores of the Bergslagen province, south central Sweden

ABSTRACT The presence of cobalt (Co) in sulphide deposits or sulphide-bearing iron oxide deposits in and around the Palaeoproterozoic Bergslagen ore province, south central Sweden, led to focused mining and extraction of this metal, particularly during the nineteenth century. Today, Co is considered a critical metal in the EU and among the more sought-after raw materials, not least due to its use in batteries for the rapidly increasing production of electric vehicles. Here we report new observations and data on Co concentrations in variably mineralised and not necessarily statistically representative samples from a suite of mainly skarn-hosted, at least locally, sulphide-dominated mineralisations from Bergslagen. While several localities that exhibit substantial Co concentrations represent deposits previously known to carry this metal (generally in a field/district or specifically in a mine), the majority are from mines or prospects in which the presence of Co have been hitherto unknown. Several of them share the enrichment of, e.g., Co and Cu, but the overall picture is one of more complex interrelations between the variable metal endowments in the known occurrences of Co in this province. While representing a modest dataset, our new observations complement previously available information on the occurrence of Co in Bergslagen and highlights both the need for, and potential of, new and more detailed studies on the distribution, mineralogy and origin of Co as well as other critical or near-critical metals in this and other ore provinces in Sweden.