Study of the patina of ancient marble sculptures by stable isotope analysis

In order to investigate the influence of weathering on the isotopic composition of marble, surface crusts of naturally weathered marble samples from different ancient quarries were studied using stable isotope mass spectrometry. Isotopic analysis shows that there is a progressive increase in the abundance of the isotopes 12C and 16O from the interior marble to the weathered crust. The same technique was also used for the analysis of marble cores taken from authentic ancient artefacts. Analogous results were obtained. Although stable isotope analysis can be a valuable help for the authentication of ancient marble sculptures, it can not provide indisputable evidence, since patina layers on sculptures and weathered stones are very different, depending on the specific weathering conditions and conservation history of the artefact.