A Non-Invasive Approach for the Identification of "Red Marbles" from Santa Maria Del Fiore Cathedral (Firenze, Italy)

The Cathedral of Santa Maria del Fiore in Firenze is externally decorated with white marble, green serpentinite and red limestones. These latter are constituted by marly and ammonitic limestones, coming from different quarries. These can be discriminated to the naked eye, but it is not possible to assign the different limestones to the quarries of provenance. In this work, the application of a portable X-Ray Fluorescence (p-XRF) for the chemical analysis of red limestones is proposed. This non-invasive technique was used on the red claddings of the Cathedral and on the limestones coming from different quarries, which were also analysed by the traditional bench XRF technique to make a comparison among the data. The outcomes show that p-XRF is a useful device capable to identify marly and ammonitic limestones and to distinguish among the different supply quarries of the marly limestones. This results in a relevant tool for the archaeometric approach and for the conservation of architectural heritage.