Rodingite from Lindås, western Norway

Rodingite within an alpine ultramafic body in the Lower Palaeozoic metamorphics of the Major Bergen Are is at present the only known occurrence of this rock type in Norway. Amphibolite dykes in ultramafic bodies have developed metasomatic zones of chlorite and tremolite or epidote and chlorite along contacts with the host rock which itself has been serpentinized dose to the dykes. The rodingite dyke is zoned with chlorite and diopside selvages along contacts with serpentinite. Microprobe analyses of the rodingite mineral assemblage, of which hydrogarnet is the most characteristic, are presented. By means of chemical analyses of the dykes, individual metasomatic zones and the ultramafic host, the nature of the mass transport during metasomatism can be demonstrated.