## 3 Results and Discussion
### Laboratory Micro-Raman Results
In fact, the presence of modified Ny, commonly characterized by ternary-oxide structures of the Pb\({}_{2}\)Sb\({}_{2}\)\(\upotimes\)Sn\({}_{x}\)O\({}_{7}\)-x/2 (Sn-modified Ny) or Pb\({}_{2}\)(ZnSb)O\({}_{6}\) (Zn-modified Ny) type [32] (respectively known since the 17 th and 20 th centuries), would lead to a shift of the aforementioned peak to -125 cm\({}^{-1}\) or to \(\sim\)145 cm\({}^{-1}\), respectively [31]. Such considerations, corroborated by the fact that, at least, traces of Zn were detected by XRF and EPMA-EDS only in the case of sample S13, lead us to exclude the employment of a modified Ny applied during a possible recent intervention. It is worth remarking that according to previously published papers, the employment of Ny was already extensively evidenced in other paintings by [PERSON] [8; 10; 12]. Concerning the green pigment of St. Vicario's cloak (S4 and S5) and St. Clemente's cloak and halo (S8 and S9, respectively), no reliable \(\upmu\)-Raman spectra were obtained. This was due to the presence of a prominent fluorescence background that almost completely covered the corresponding Raman profiles, making the molecular characterization of such samples neither feasible nor accurate. The \(\upmu\)-Raman analysis of the flesh-toned micro-fragments (sampled at points S6, S10, S19, S22, S23, S25) furnished evidence of a complex molecular composition characterized by a mixture of several compounds. In particular, Figure 7 reports three representative photomicrographs and corresponding \(\upmu\)-Raman spectra, collected on different flesh-toned micro-fragments (sampled at point S6, S10 and S22) of the painting, as example. More in detail, the \(\upmu\)-Raman profile collected on S6 (Figure 7d) indicates the presence of minium,  
Figure 6: (**a**) Photomicrograph, in white reflected light, and (**b**) \(\upmu\)-Raman spectrum collected on a yellow-orange micro-fragment (sampled at point S13) of the _“The Glory of St. Barbara”_ painting. through the detection of its main peak centered at ~121 cm\({}^{-1}\) (due to O-Pb-O angle deformations), along with other contributions falling at ~151 cm\({}^{-1}\), ~311 cm\({}^{-1}\), ~390 cm\({}^{-1}\) and ~548 cm\({}^{-1}\). Furthermore, in the case of the \(\upmu\)-Raman spectrum collected on S10 (Figure 7e), vermilion can be distinguished, by its typical triplet of low-frequency peaks centered at ~252 cm\({}^{-1}\) (A\({}_{1\text{g}}\)), ~288 cm\({}^{-1}\) (E\({}_{\text{g}}\)) and ~347 cm\({}^{-1}\) (E\({}_{\text{g}}\)). The \(\upmu\)-Raman spectrum of sample S22 (Figure 7f) shows, among other features, a strong and sharp Raman band at ~1051 cm\({}^{-1}\), indicating the application of a white lead pigment. Generally, the occurrence of such peak is considered to be related to degradation phenomena involving lead-rich materials of the original portion of the canvas [33; 34], consequently the prolonged exposure of the painting with air and biodeteriogenic agents (i.e., bacteria and fungi). Under such circumstances, the production of lead sulfide (PbS) and lead dioxide (plattnerite, PbO\({}_{2}\)) onto the pictorial layer is highly favored, resulting in a blackening of the original white coloration in favor of a pinkish nuance. Based on the aforementioned results, the flesh-toned colorations were reasonably realized by mixing minium with dilute amount of vermilion and white lead in different proportion, depending on the desired pinkish shades, in good agreement with the previous analysis of the pink layer by XRF and EPMA-EDS and literature results [8; 10; 12]. It is worth noting that in all micro-fragments the presence of an organic compound was identified, through the observation of contributions falling at ~942 cm\({}^{-1}\), ~1308 cm\({}^{-1}\) and ~1406 cm\({}^{-1}\) (Figure 7d-f), supporting the hypothesis that it is in fact distributed uniformly onto the whole surface of the artwork.