The work combines the authors'observation that the details of marble statues that have already been lost from the calcite surface are preserved in the gypsum layer, with their research on the mechanism of marble sulfation, to lead to a consolidation of the gypsum, transforming it back to calcium carbonate (calcite) using carbonate ions in solution. Research shows the mechanism of the conversion of gypsum to calcite, the rate determining steps being the desorp tion and diffusion of COÈ7. The reproduction of the surface detail and the improvement of the mechanical properties were very satisfactory. See also AATA 19-1782, 19-1783, 20-1528, 20-1529, and 21-2123 for more information on marble sulfation.