 Magnesium content determines the proportion of talc and/or magnesite and aluminium-calcium-sodium content determines the proportion of amphibole and/or chlorite.Several minerals are diagnostic of talc carbonated ultramafic rocks;

At amphibolite facies, the diopside-in isograd is reached (dependent on carbon dioxide partial pressure) and metamorphic assemblages trend toward talc-pyroxene and eventually toward metamorphic olivine.Serpentinisation of olivine