Status-report on talc-prospecting in Helgeland, northern Norway.

Abstract

A prospecting programme for talc has been carried out in Helgeland. The results are both good and bad; a new talc deposit has been found in Kvanndalen, a few km west of Altermark. The deposit are exposed, and the size is not yet known, except that the maximum width is around 50 metres. To be able to use th ore, there must either be a market for the assemblage talc-breunnerit-olivine, or it must be possible to remove the olivine. A further deposit of interest occurs in Misvær. Otherwise, talc is rather uncommon in the numerous ultramafic lenses around the Høgtuva-, Sjona- and Svartisen windows. The ultramafic lenses are dominated by the metamorphic assemblage enstatite-anthophyllite-carbonate with or without olivine. It is concluded that the metamorphic grade has, in general, been too high in the western area and that possible pre-existing talc-carbonate assemblages have been altered to the minerals above. The deposit in Kvanndalen probably represent the margin of what can be termed the Altermark Talc Province. Only olivine has been included in the talc-carbonate assemblage, while bodies further to the west carry olivine, enstatite and anthophyllite.