Chemical analyses of dolerites and metadolerites from the Scourie-Loch Laxford area have been made, together with analyses of amphiboles and a pyroxene from these rocks. Chemical variation within the dykes as originally emplaced has been investigated. Introduction of material during metamorphism is limited, only potassium showing a marked increase in concentration. In the least-altered dykes a relationship between degree of clouding in felspar and amount of H 2 O (super +) present is indicated. Chemical analyses and optical properties of amphiboles show no distinctive trends which could be associated with the progress of the metamorphism.