A long-lasting fluid infiltration event influenced mineral reactions during retrograde metamorphism in parts of the southern margin zone of the Damara Orogen. Talc was formed in many places in metadolomites in voluminous masses by infiltration of silica-bearing aqueous fluids into the hot rock. The Ca from the decomposition of dolomite did not precipitate in the form of calcite because it was removed by the metasomatic fluids. At the end of this process talc decomposed under the influence of CO2 -rich fluids to form magnesite + quartz.