## 3 Results and Discussion
### Case Study 2: Bronze Objects
#### 3.2.3. SEM-EDX Analysis  
Further semi-quantitative analysis was performed on the outer surface of the metal fragments (Table 2). The acquired results provided the percentages of the identified chemical elements on alloy-burial environment interaction products.  
The superficial layers of the two belt fragments were similar in composition (i.e., both had a high tin content, followed by a copper content of around 5%). As has been noted, the helmet fragment differed because lead was present (which was also highlighted in the XRF analysis). It, too, had a high tin content (around 40%) and copper (around 25%). The high  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**F1 Fragment** & **1** & **2** & **3** \\
**Element (Weight \%)** & & & \\ \hline Aluminum & 2.5 & 1.6 & 1.4 \\ Silicon & 5.9 & 4.2 & 4.1 \\ Phosphorus & 0.8 & 0.8 & 0.7 \\ Iron & 2.2 & 2.0 & 2.2 \\ Copper & 4.2 & 5.0 & 4.5 \\ Tin & 84.4 & 86.5 & 87.1 \\ \hline
**F2 Fragment** & & & \\
**Element (Weight \%)** & & & \\ \hline Aluminum & 0.6 & 0.9 & 14.7 \\ Silicon & 4.5 & 5.3 & 4.2 \\ Phosphorus & 0.7 & 0.5 & 0.5 \\ Iron & 2.0 & 1.8 & 1.8 \\ Copper & 7.6 & 8.6 & 6.1 \\ Tin & 84.5 & 82.9 & 72.7 \\ \hline
**H1 Fragments** & & & \\
**Element (Weight \%)** & & & \\ \hline Aluminum & 0.9 & 0.7 & 0.9 \\ Silicon & 7.1 & 7.1 & 7.4 \\ Calcium & 0.6 & - & - \\ Iron & 2.6 & - & - \\ Copper & 25.4 & 25.7 & 29.3 \\ Tin & 37.8 & 40.3 & 38.1 \\ Lead & 25.6 & 26.3 & 24.2 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Semi-quantitative analyses by SEM-EDS on the metal fragment surface.  
Figure 6: Images of the three bronze fragments at high magnification, acquired using a digital optical microscope and corresponding XRF spectra.  
tin content in each of the samples may have been the result of a decuprification process or the selective dissolution of copper that causes the replacement of metal in corroded products [32; 33]. Further, it could be linked to the so-called tinned surfaces (when molten tin is applied to bronze) and layers of both the \(\eta\) (eta) and the \(\Sigma\) (epsilon) phases, which develop by interdiffusion between the bronze and the molten tin, create layered structures in the following sequence: surface tin, eta phase, epsilon phase, and substrate bronze [34]. In addition, the presence of elements such as aluminum and silicon may be due to their migration from the soil to the porous external layers of the samples [35]. A remarkable feature that all the samples have in common is the absence of chlorine among the corrosion products. This may be linked to the microenvironmental conditions. The absence in this area of chlorine compounds suggests that the copper present is cuprite or, in the first two samples, copper phosphates (which is associated, e.g., with decomposing buried bones and other organic or inorganic phosphorus-containing materials) [36; 37].  
Further analysis would be necessary to evaluate whether the distribution of chemical elements was attributable to the patina (the result of interaction with the burial environment) or the original composition of the alloy. This information could be useful when attempting to verify the expected production period, which may be hypothesized in terms of archaeological or stylistic phases.