## 2 Materials and Methods
### Sampling Methodology and Analytical Techniques
The chemical analysis of the collected fragments was determined by XRF with a wavelength dispersion spectrometer ARL Advant-XP (Thermo Fisher Scientific, Waltham, MA, USA) [21]. The instrument consisted of an X-ray tube with a Mo target and an SSD Peltier-cooled detector (10 mm\({}^{2}\) active area and resolution of \(<\)155 eV at 10 kcps). The system performs a simultaneous multi-element analysis in the element range from Na (11) to U (92). A maximum voltage and current of 50 kV and 1500 \(\mu\)A, respectively, were used to excite the secondary fluorescence X-rays. A collimator with a diameter of 1 mm was used to collect the emitted secondary X-rays from a surface area of about 0.79 mm\({}^{2}\) in the air [22]. This technique allowed the determination of the major elements, expressed as a percentage by oxide weight (SiO\({}_{2}\), TiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), Fe\({}_{2}\)O\({}_{3}\), MnO, MgO, CaO, Na\({}_{2}\)O, K\({}_{2}\)O, and P\({}_{2}\)O\({}_{5}\)), and of the following trace elements reported in ppm (parts per million): Ba, Cr, Ni, Pb, Rb, Sr, V, Zn, Zr, Nd, and S [23]. The accuracy of the instrument, estimated based on the results obtained for international standards of geological samples, and the precision, expressed as the standard deviation of replicated analyses, were between 2% and 5% for the major elements and between 5% and 10% for trace elements. The detection limit (0.01% for major oxides) was estimated to be close to ppm for most trace elements, except for S, for which a detection limit of 50 ppm was considered. The processing of the acquired intensities and the correction of the matrix effect were performed according to the model proposed by [PERSON] and [PERSON] [24]. The qualitative data obtained were expressed as the single element weight. In order to validate the L.O.I. procedure on selected samples of mortar (from n. 9 to n. 17) bricks (samples 2 and 6) and clays (samples 18 and 19), calcimetric analyses were carried out (gas volumetric method) [25,26]. The carbonate content, if present, was determined on the basis of the chemical reaction between a known quantity of sample (0.500 g) and 10% hydrochloric acid (HCl) according to the following chemical reaction:  
\[\text{CaCO}_{3}+2\text{HCl}\ \rightarrow\text{CO}_{2}+\ \text{H}_{2}\text{O}+\ \text{CaCl}\]  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**(a)**} & \multicolumn{10}{c}{**Bricks**} & \multicolumn{10}{c}{**Clays**} \\ \hline  & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **18** & **19** \\ \hline SiO\({}_{2}\) & 51.58 & 54.11 & 55.50 & 55.49 & 56.19 & 52.47 & 53.74 & 53.94 & 68.21 & 64.73 \\ TiO\({}_{2}\) & 0.65 & 0.66 & 0.81 & 0.66 & 0.77 & 0.67 & 0.66 & 0.69 & 0.23 & 0.22 \\ Al\({}_{2}\)O\({}_{3}\) & 12.39 & 14.38 & 16.33 & 14.56 & 15.27 & 12.86 & 14.43 & 13.74 & 8.71 & 9.06 \\ Fe\({}_{2}\)O\({}_{3}\) & 5.55 & 6.04 & 6.49 & 6.06 & 6.25 & 5.56 & 6.40 & 6.29 & 2.14 & 2.13 \\ MnO & 0.12 & 0.14 & 0.13 & 0.12 & 0.14 & 0.12 & 0.13 & 0.14 & 0.04 & 0.07 \\ MgO & 5.13 & 5.65 & 4.12 & 5.93 & 4.41 & 4.10 & 4.29 & 4.30 & 3.37 & 3.81 \\ CaO & 17.03 & 13.39 & 9.28 & 11.77 & 10.55 & 15.95 & 15.29 & 16.17 & 8.65 & 11.18 \\ Na\({}_{2}\)O & 2.41 & 2.03 & 1.26 & 2.06 & 1.72 & 1.92 & 3.27 & 2.77 & 2.01 & 1.76 \\ K\({}_{2}\)O & 1.24 & 1.98 & 2.75 & 2.12 & 2.54 & 2.30 & 1.00 & 0.94 & 2.26 & 2.21 \\ P\({}_{2}\)O\({}_{5}\) & 0.55 & 0.20 & 0.33 & 0.23 & 0.21 & 0.33 & 0.14 & 0.34 & 0.11 & 0.14 \\ L.O.I.