## 4 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c} \hline \hline
**Sample** & **As** & **Ba** & **Br** & **Co** & **Cr** & **Cs** & **Cu** & **Ga** & **Nb** & **Ni** & **Pb** & **Rb** & **Sn** & **Sr** & **Th** & **V** & **Zn** & **Zr** \\ \hline MA2 & 23.1 & 350 & 60.2 & 5.6 & 45.4 & 18.6 & 23.7 & 36.0 & 31.4 & 11.6 & 59 & 270 & 28.4 & 85 & 36.4 & 50.4 & 77 & 300 \\ MA3 & 17.3 & 360 & 52.4 & 5.1 & 47.4 & 22.2 & 27.0 & 37.1 & 32.3 & 13.3 & 51 & 250 & 23.2 & 65 & 37.0 & 56.1 & 87 & 300 \\ MB1 & 51.9 & 520 & 30.6 & 8.4 & 46.4 & 20.8 & 67.2 & 34.5 & 29. LOI (2.7%) concentrations, among all samples. The low LOI (2.7-11.2%) in all samples, when compared to other studies, e.g., [8,40], can be related to the high percentage of clay minerals and its release of OH- and calcite release of CO2 [41]. _Nucleus_ renders (layer 1--_nucleus_ upper zone, and layer 2--_nucleus_ lower zone) also displayed higher content of Fe2O3 (8.1-11.2%, except in sample MC1 with 7.6%), Al2O3 (29.3-36.0%) and lower SiO2 content (31.8-38.5%), when compared to _rudus_ (MD3) and _statumen_ (MA1) render samples, which may be the result of ceramic powder presence in nucleus render composition. The higher content of Fe2O3 is responsible for the rose ochre color, that can be associated with the brick fragments or powder mixed in the mortar [38], and may indicate that iron is in its oxide form. Additionally, layer 1 showed higher CaO content (3.6-5.5%, except in sample MB1 with 2.1%) than layer 2 (1.5-2.4%). The higher CaO content in layer 1 may result from the influence of the composition of the bedding mortar that previously existed above the nucleus layer (although was not visible during sampling) and could be mixed in the nucleus upper zone. According to [PERSON] [33], it was composed by lime and very fine marble dust. In layer 1, MA2 and MC1 samples showed the highest CaO content, with 5.1% and 5.5%, respectively. The highest content in Al2O3 was observed in layer 2 (34.1-36.0%). The higher Cl content was found on the _nucleus_ upper layer (layer 1), which may be the result of capillary rise with chloride soluble salts through the mosaic floor and evaporation occurring at the outer surface of the outer layer, and as a result higher Cl concentration was observed in this layer [42]. Previous studies about the chemical characterization of archaeological and ceramic materials used the hierarchical cluster analysis on chemical data to obtain a more robust interpretation [43,44]. The cluster analyses (Ward linkage) of layers 1 and 2, separated sample MC1 from the others, and defining two other subgroups, one with MA3, MB1, and MA2 samples, and a second one with MB2, MC4, MC3, MC2, MD2, and MD1 samples (Figure 8a). The variables cluster analysis also revealed that Al2O3 and SiO2 present a distinct concentration pattern from the other major elements, in agreement with previous analysis (Figure 8b). An ANOVA 1-way analysis of these two groups revealed significant statistical differences in Al2O3 and CaO (\(p<0.05\)). The groups descriptive statistics showed that Al2O3 concentration mean for layer 2 (36.62%) was higher than for layer 1 (31.68%), and that CaO mean for layer 1 was higher than for layer 2, with 4.04% and 1.90%, respectively. Despite differences identified, all the other variables did not present significant differences. Additionally, discriminant analysis based on the chemical composition of each nucleus layer (1 and 2) revealed that samples MC2 and MC4 from layer 2 showed more affinity with layer 1, and samples MA2 and MD1 from layer 1 revealed more affinity with layer 2. This may result from sampling contamination due to the small thickness of this layer. As this roman pavement is an archaeological heritage integrated in a museum, it is not possible to collect more samples. Figure 8: Cluster analysis of layer 1 and 2: (**a**) samples; (**b**) major elements. Relatively high trace elements As, Pb and Cu contents (Table 3), when compared to other studies [38,40], were found.