Dispersal of tungsten in glacial drift and humus in Bergslagen, southern central Sweden

Since the late part of the 19th century prospecting for W in the western world has been based mainly on the mechanical concentration of heavy minerals in sediments (panning), followed by visual and chemical analyses of the heavy-mineral fraction. Since the early 1970's, W prospecting in Sweden has been based on the use of heavy-mineral concentrates from till.In tests performed in a scheelite-mineralized area in the Bergslagen area of central Sweden, samples from the A- and C-horizon of the podzolic profile have been collected along grid lines across the ore as well as down-ice along the direction of final glacial transport from the ore. The purpose of the study was to test which sample types should be used in geochemical prospecting for W in the region.The results show that all the sample types studied can be used in geochemical prospecting for W in southern central Sweden. The heavy-mineral concentrate of till is primarily recommended for use at a regional and local scale. Humus is given the lowest priority of the sample types studied because of the poor analytical reproducibility for some samples with high values of W.