Abstract

The area of Bergslagen in central Sweden comprises the most important known tungsten province in Scandinavia. Several mines have been in operation for brief periods. Currently only the deposits at Yxsjoeberg and Hoegfors are in production. Most scheelite deposits in the area are confined to skarn-limestone in the vicinity of late Svecokarelian granitic rocks. Only a few deposits of vein mineralization are known where wolframite is the principal tungsten mineral. This paper gives a general description of the tungsten occurrences in central Sweden and deals in greater detail with the deposits at Elgfall, Snoeaan, Laggarudden, Yxsjoeberg, and Tyfors.From a general point of view the tungsten deposits at Elgfall, Snoeaan, and Laggarudden are of contact metasomatic origin. However, it is proposed that not only contact metasomatic processes but also thermal metamorphism and sometimes hydrothermal processes took part in the formation of the tungsten ores. At Elgfall and Snoeaan the tungsten mineralized skarn bodies occur adjacent to a granitic rock whereas at Laggarudden the tungsten-skarn is in contact with a pegmatite. No definite interpretation of the genesis of the Yxsjoeberg deposit can be made. Most evidence suggests that the stratabound deposit at Yxsjoeberg is of epigenetic origin and formed by hydrothermal solutions originating most probably from an acid magma.For the Tyfors vein deposit a two-stage mineralization process seems likely. The first stage involved formation of wolframite at high temperature and pressure, the second stage a hydrothermal formation of sulfides.

First Page Preview

First page PDF preview
You do not currently have access to this article.