The stones used for building the apse of the Pisa’s Cathedral (Italy)

A detailed knowledge of the building materials and of their main characteristics is a fundamental pre-requisite for a good stonework’s restoration project. Nowadays Computer Aided Design (CAD) can be considered as an interesting tool for the achievement of stonework mapping and, more generally, to the management of a full restoration project. This paper presents the mapping of the building stones used in the apse of the Pisa’s Cathedral (XI century), with the scope of highlighting the potential of photogrammetry and CAD techniques in the field of restoration and conservation of stonework. Once the survey of the apse masonry had been realized and the main geometry of each ashlar was detected, the building materials have been mostly identified by stone-to-stone visual inspection. For the recognition of the stones used for building the apse of the Pisa’s Cathedral, the macroscopic characteristics widely described in several papers on the stones of medieval buildings in Pisa (Franzini & Lezzerini, 2003 and references therein) were exploited, while for marbles analysis traditional methods, such as textural features, accessory minerals and C-O stable isotope data (Moens et al., 1992; Gorgoni et al., 2002; Capedri et al., 2004) were applied. Based on collected data, the Apse of Pisa’a Cathedral was mostly made up of Mt. Pisano and Apuan marbles and black limestones quarried at some kilometres northwest from Pisa in the Monti d’Oltre Serchio area. Re-used Marbles from quarries located in Eastern Mediterranean area (Turkey and Egypt) characterise the first construction phase of this monument. The lithotypes identified in intarsia of the apse are serpentinites of unknown origin, used as decorative stones for their marble-like qualities, and small elements of red limestone probably belonging to the Scaglia Rossa Formation of the Tuscan sequence.