The Building Stones of Prato’s Cathedral and Bell Tower, Italy

Abstract

This study defines the assemblage, lithotypes and mechanical parameters of the building stones used for the external cladding of Prato’s Cathedral and Bell Tower (XIV century), now subject to extensive conservation work. By means of a drone flight, a full 3D model of the Cathedral and Bell-Tower complex was developed with photoplanes of the façades. On this basis, a GIS of the façades with all the stone elements embedded was developed. Historical data and organoleptic analysis enabled the identification of the types of the stones constituting the cladding. The results show that the building stones used for the cladding are all local historical stones, namely white Alberese and Palombini limestones, green Verde Prato peridotites, and grey Pietra Serena sandstone. The quarries of provenance of these stones were determined, along with their physical-mechanical properties and decay processes, in order to contribute to conservation works according to authenticity and integrity principles.