Na-metasomatism in the form of albitisation is regionally extensive in the Precambrian crust of southern Scandinavia and is particularly widespread in the Bamble Sector,the Kongsberg-Modum Sector and the Norwegian part of the Mylonite Zone.Sites of albitisation outside these belts are associated with hyclrothermal breccia pipes and fracture-bound alteration.The albitites are composed of near end-member sodic plagioclase(An_(0-5)Ab_(94-99)) with minor carbonate(calcite and dolomite),rutile,clinopyroxene(En_(30)Fs_(21-23)Wo_(47-49)).amphibole(edenite-pargasite),quartz.titanite.tourmaline,epidote(Fe~3 0.20-0.85 a.p.f.u) and chlorite(Mg’ 0.81 0.89).The albitites have been studied in detail in the region around the town of Kragere,and are described as albitisation along veins,as breccias,albitic felsites.massive carbonate-bearing albitites and megascale clinopyroxene-titanite-bearing albitite.The strong fluid control on their formation is illustrated by the veining and mineral replacement reactions,showing fluid transport by a H_2O-CO_2 fluid rich in Na.depleting Fe and Mg from the host rock,in accordance with calculated mass transfer.A study of the mineralogical replacement reactions in combination with a regional compilation has demonstrated the relationship between metasomatic processes and the for mation of apatite.rutile and Fe deposits.The albitites occur spatially associated with other metasomattc rocks such as scapolitised metagabbros.We document that metasomatism is an important mineral- and rock-forming process in the continental crust,which in the Bamble Sector is a part of the tectonometamorphic evolution of the Sveconorwegian orogen. Na-metasomatism in the form of albitisation is regionally extensive in the Precambrian crust of southern Scandinavia and is particularly widespread in the Bamble Sector, the Kongsberg-Modum Sector and the Norwegian part of the Mylonite Zone .ites of albitisation outside these belts are associated with hyclrothermal breccia pipes and fracture-bound alteration. The albitites are composed of near end-member sodic plagioclase (An_ (0-5) Ab_ (94-99)) with minor carbonate (calcite and dolomite), rutile, clinopyroxene (21-23) Wo_ (47-49) amphibole (edenite-pargasite), quartz.titanite.tourmaline, epidote (Fe ~ 3 0.20-0.85 apfu) and chlorite (Mg ’0.81 0.89) .The albitites have has studied in detail in the region around the town of Kragere, and are described as albitisation along veins, as breccias, albitic felsites .massive carbonate-bearing albitites and megascale clinopyroxene-titanite-bearing albitite. The strong fluid control on their formation is illustrated by the veining and mineral replacement r eactions, showing fluid transport by a H_2O-CO_2 fluid rich in Na.depleting Fe and Mg from the host rock, in accordance with the calculated mass transfer. A study of the mineralogical replacement reactions in combination with a regional compilation has demonstrated the relationship between metasomatic processes and the for mation of apatite.rutile and Fe deposits. The albitites occur spatially associated with other metasomattc rocks such as scapolitised metagabbros.We document that metasomatism is an important mineral- and rock-forming process in the continental crust, which in the Bamble Sector is a part of the tectonometamorphic evolution of the Sveconorwegian orogen.