Archaeometric study of fictile tubes from three churches in Milan

Fictile tubes (or vaulting tubes) are architectural elements that sustain and underline the shapes of cupolas and vaults. Several of these, sampled in three churches of Milan (S. Ambrogio, S. Lorenzo and Duomo) have been recently dated at the Archaeometry Laboratory of Milano Bicocca University. These architectural elements, differently shaped, styled and sampled from different structures, were all produced, according to thermoluminescence (TL), in the period 970-1080 AD. Energy dispersive X-rays fluorescence (EDXRF) measurements were performed to obtain the elemental composition of the clays and to attempt a classification of the samples. Multivariate PCA (principal components analysis) analyses and HCA (hierarchical clusters analysis) did not show any grouping of similarity. On the basis of the results, a tentative historical interpretation could be proposed.