## 3 Results
### XRF Analyses  
The chemical composition (major and trace elements) of all of the samples collected was determined by XRF. Table 2 and Figure 3 show the data relating to the chemical elements analyzed in the different samples for both the major elements expressed using the oxide concentration in the weight percentage and trace elements concentration expressed in ppm. In all of the samples, the oxides were characterized by high values of SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), and CaO, followed by Fe\({}_{2}\)O\({}_{3}\) and MgO. In addition to the tables, the chemical analyses of all samples were interpreted using binary diagrams of the variation in every single chemical element with respect to silica. In each diagram, the brick samples are colored in red, mortar samples in green, clay samples in yellow, tracbyte samples in pink, and sand samples in blue. Figure 2: Classification according to [PERSON] [28] of: (**a**) mortar samples and (**b**) natural samples. The yellow circle represents the silty sand samples, the orange circle represents the sand samples, the blue circle represents the loam samples, the green circle represents the silty clay sample, and the gray circle represents the clayey sand sample. Brick samples (colored in red in the diagrams of Figure 4) were generally characterized by a low value of silica with respect to the other samples, a high value of Al\({}_{2}\)O\({}_{3}\) (Figure 4a), Fe\({}_{2}\)O\({}_{3}\) (Figure 4b), MnO (Figure 4c), MgO (Figure 4d), CaO (Figure 4e), and Na\({}_{2}\)O (Figure 4f), and more similar values of the trace elements, such as Co (Figure 4h) and Cr (Figure 4i), as shown in Table 2.  
Figure 4: _Cont._  
Figure 3: Bar chart showing the relative abundances of the major oxides in the different types of samples analyzed in this work. Each line represents the average value of those expressed in Table 2.  
Figure 4: _Cont._  
The opposite was observed for the clay samples (colored in yellow in the diagrams in Figure 4), with a higher value of silica but lower values of the other major oxides with respect to the brick samples and low values of the trace elements Co (Figure 4h), Cr (Figure 4i), and Ni (Figure 4j) (Table 2). The results obtained for both major and trace elements could have confirmed that the clay collected was not used to build the bricks. Mortar samples (colored in green in the diagrams in Figure 4) showed low values of Al\({}_{2}\)O\({}_{3}\) (Figure 4a), Fe\({}_{2}\)O\({}_{3}\) (Figure 4b), and MgO (Figure 4d), similar to the clay samples, but a high value of CaO (Figure 4e), as shown in Table 2, and similar to the brick samples (Table 2a). Regarding the trace elements, mortar samples were characterized by low values of trace elements, such as Co (Figure 4h), Cr (Figure 4i), Ni (Figure 4j), and Rb (Figure 4k), with respect to the other samples. Table 2 also shows the XRF data obtained from the analyses of the trachyte samples, which were characterized by higher values of Al\({}_{2}\)O\({}_{3}\) (Figure 4a), Fe\({}_{2}\)O\({}_{3}\) (Figure 4b), MgO (Figure 4d), and K\({}_{2}\)O (Figure 4g) and lower values of MnO (Figure 4c), CaO (Figure 4e), and Na\({}_{2}\)O (Figure 4f). In the diagram in Figure 4, the trachyte samples are colored pink and show a high value of Rb in Figure 4k. Finally, Table 2 shows the data obtained on the sand samples (colored in blue in the diagrams of Figure 4) with different values of silica (between 53.62-66.37), but generally low values of CaO and Na\({}_{2}\)O. In geochemical analysis, L.O.I. represents the H\({}_{2}\)O released by clay and gypsum minerals, as well as the CO\({}_{2}\) released by calcite and dolomite. Mortar samples were enriched in calcite and dolomite, and showed higher values of L.O.I. and carbonate contents. Regarding the brick samples, they presented lower values of L.O.I.