Geochemical and isotopic provenance determination of gypsum used for stucco artworks: application to Florentine stucco reliefs

Gypsiferous rocks of Tuscany and derivated materials (i.e. alabaster, stucco and gesso) have been frequently used as sculptural materials. Remarkable examples are attested from the Renaissance Florence. At the junction of two ongoing programs, dealing respectively with the study of 15th century stucco reliefs (called Madonne di gesso) and the provenance of European alabasters used in artworks, an investigation on raw gypsum supply was conducted via a geological survey in the surroundings of Florence. Looking for geochemical provenance markers, a multi-analytical approach was carried out on3 0 geo-referenced rock samples. In particular, trace elements, related, both to gypsum and synsedimentary minerals, and gypsum multi isotopic fingerprints (S, O, Sr) were tested. The results obtained are discussed, disclosing insights in the geo-sourcing of raw materials used for stucco reliefs in Florentine workshops.