Golden folder from the Wall Mosaic of S. Giovanni in Fonte. Remarks and Scientific Analyses on the Constituent Materials

For conservation and restoration actions to be effective and respectful of cultural instances, it is crucial to acquire the knowledge framework of the examined monument by following a method which allows systematically collecting all the information needed to define its state of conservation. Managing complex data about a cultural asset requires a methodological guide that enables to coordinate information from multidisciplinary skills systematizing it and highlighting relations and connections between the various levels of knowledge. Based on such considerations, a study on the mosaics of the dome of the baptistery of San Giovanni in Fonte was carried out. The dome is located down the right nave of today's Basilica di Santa Restituta and is attached to the Cathedral. Its mosaics are considered as one of the most important expressions of paleo-Christian art in Italy, as a rare example of wall mosaic decoration still existing in the south of the country. At the ridge of the octagonal-based dome, on a starry sky background, stands out the "Chrismon", i.e. the monogrammatic cross symbolizing the glorious Christ with the letters alpha and omega hanging from his arms. Based on a previous methodological study, in this paper we present new results, which, placing particular attention to the dome of the baptistery, focus specifically on a micro sample, called "cartellina d'oro", belonging to the mosaic of vault and more specifically to the monogrammatic cross, placed in the center of the dome. The availability of innovative analytical measures, allowed to carry out further laboratory investigations, in order to deepen the existing knowledge about the Byzantine mosaic and thus be a useful tool to go back to the artistic techniques used in paleo-Christian era.