Schists with the mineral assemblage quartz-albite-dolomite-green biotite-aegirine-rie-beckite, occur as thin bands ½ to I metre wide, within albite-epidote greenschists and garnet-plagioclase quartzo-feldspathic schists of the oligoclase zone of South Westland, New Zealand. Optical and chemical date show that the aegirine contains a negligible amount of the jadeite molecule whilst the optics of the riebeckite indicate that it is a member of the arfvedsonite-riebeckite series. A typical schist has a high soda content, a molecular ratio Na2O+K2O÷ Al2O3>1, a high oxidation ratio, and a low lime content. These data, together with the fact that the calculated mineral assemblage of the molecular mesonorm is identical with that of the rocks, are taken as evidence that the schists result from recrystallization of a rock with unusual chemical composition under P-T conditions on the boundary between those giving rise to the greenschist facies and the almandine-amphibolite facies.