Abstract. The REE-Cu-Fe-(Au) deposits of Bastnäs-type in the Bergslagen ore province in central Sweden have a long history of mining as well as scientific study and discovery. Yet, relatively little information on their timing of formation has been available, and their overall genesis remains unclear. Here we present data and observations on an uncommon style of Bastnäs-type REE silicate mineralisation, from the Högfors deposit. It represents the only direct observation of this type of mineralisation that is apparently stratabound, inter-layered in a banded iron formation (BIF). The deposit is located in the northern part of the Riddarhyttan district. Here, cerite and västmanlandite-dominated, banded REE silicate mineralisation occurs within a hematite-dominated, quartz-banded iron formation together with modest amounts of associated, amphibole-dominated Fe-Mg-Ca skarn assemblages. The REE minerals, as well as the associated iron oxides, are extensively recrystallised to a granoblastic texture. Furthermore, these banded assemblages are extensively folded, and we conclude that REE mineralisation formed prior to the polyphase deformation and regional metamorphism associated with the c. 1.90-1.80 Ga Svecokarelian orogeny. These observations contradict post-orogenic processes as responsible for the Bastnäs-type REE deposits, and support a model involving syn-volcanic (Svecofennian), magmatic activity.