ESR spectroscopy as a tool for identifying joining fragments of antique marbles: The example of a pulpit by Donatello and Michelozzo

ESR spectroscopy is one of the physicochemical techniques used to character ize archaeological white marbles and obtain information about their quarrie s of provenance. This is done by measuring selected spectral features of th e Mn2+ impurity ubiquitously present in marbles and developing a statistica l classification rule from the variable vectors measured for a significant number of samples of known provenance (the quarry database). Now we shaw th at the overall variability exhibited by the same spectroscopic features dec reases rapidly with the linear dimensions of the sampled block and can be u sed to distinguish fragments belonging to the same piece of stone from thos e simply originating from the same quarry. Application of the method to the seven marble panels of the Donatello pulpit in Prato (Tuscany) shows that they have all been cut from the same single block and their different degra dation must be ascribed to differential weathering and to the different con servation treatments undergone in the past. The limits and possible drawbac ks of the method are also discussed. (C) 2000 Academic Press.