Coarsely crystalline metacarbonates exhibiting post-metamorphic exaggerated grain growth fabrics and evidence for hydrothermal alteration have been investigated by means of various methods (e.g. thin section analysis, cathodoluminescence microscopy and the electron microprobe). Each rock type, consisting of graphite-bearing sparry calcite marbles and sparry dolomite marbles, exhibits a complete transitional fabric development from host rock to marbles showing exaggerated grain growth. The final stage in the coarsening process leads to the growth of sparry calcite rhombohedral blasts and sparry dolomite porphyroblasts. The dominant mechanism in the sparry calcite marble is grain boundary migration, whereas the sparry dolomite marble formed by a combination of solid state processes (coalescence crystallization) and hydrothermal processes. The driving force behind this process is the reduction of interfacial free energies, leading to an increase in grain size and a reduction of the grain boundary surface area. Grain-scale fluid-rock interaction resulting from the infiltration of Fe-/Mn-rich fluids created a very complex series of cathodoluminescence fabrics in the sparry dolomite marbles. Unique zonation assemblages, formed by diffusion processes and solution/precipitation occur all along the grain boundaries and microcracks. These form an interconnected Fe-rich network and attest to extensive and active material transport. The gradual and abrupt changes in the Fe and Mn contents point to cyclical or episodic fluid influxes.