## 3 Results and Discussion
### In Situ XRF Results
\begin{table}
\begin{tabular}{c c} \hline \hline
**Analyzed Point** & **Elemental Composition by XRF** \\ \hline S1 & S, Ca, Pb, Fe, Hg, Cl, K, As, (Zn, Se, Mn, Ba, Sr, Rb, Cr, Mo, Zr) \\ S2 & Ca, S, Fe, K, Cl, Pb, (I, Hg, As, Ti, Mn, Zn, Ba, Sr, Cr, Mo, Zr, Rb, Se) \\ S3 & S, Pb, Ca, Cl, As, Fe, K, (Ti, Se, Hg, Mn, Cd, Zn, Sn, Ba, Rb, Sr) \\ S4 & S, Pb, Ca, Cl, As, K, Fe, Co, (Cu, Sb, Ti, Hg, Se, Ni, Mn, Zn, Sr, Rb, Ba, Cd, Cr, Mo) \\ S5 & S, Pb, Ca, Cl, As, K, Fe, Co, (Ni, Mn, Cu, Se, Hg, Zn, Sb, Rb, Ba, Sr, Cd, Mo) \\ S6 & S, Pb, Cl, As, Ca, Fe, K, Hg, (Se, Ti, Cd, Zn, Mn, Rh, Mo) \\ S7 & S, Pb, Ca, Cl, Fe, K, Ti, Fe, Zn, (Se, Sb, Mn, Ba, Cd, Rh, Sr) \\ S8 & S, Ca, Pb, Fe, Cl, As, K, Mn, (Hg, Ti, Zn, Se, Ba, Sr, Rb, Cr, Cu, Cd, Mo, Zr) \\ S9 & S, Pb, Ca, Cl, As, Fe, K, (Mn, Se, Ti, Zn, Hg, Cu, Rb, Ba, Sr, Cd, Mo) \\ S10 & S, Pb, Cl, As, Ca, Fe, Hg, (Co, Mn, Se, Zn, Ti, Ni, Rb, Cd, Ba, Sr, Mo) \\ S11 & S, Pb, Ca, Cl, As, Fe, K, Hg, (Co, Mn, Se, Zn, Ti, Ni, Rb, Cd, Ba, Sr, Mo) \\ S12 & S, Pb, Cl, As, Ca, K, Co, (Fe, Se, Ti, Zn, Cd, Mn) \\ S13 & S, Pb, Ca, Fe, Cl, As, Sb, Hg, (I, Mn, Zn, Cd, Ba) \\ S14 & S, Pb, Cl, As, Ca, K, Hg, Fe, Co, (Zn, Cd, Sn, Ti, Mn) \\ S15 & S, Pb, Cl, As, Ca, K, Co, Fe, (Se, Zn, Nd, Gd, Rh, Mn) \\ S16 & S, Pb, Ca, Cl, As, K, Fe, Co, (Ti, Ni, Se, Cu, Zn, Ba, Mn, Rh) \\ S17 & S, Ca, Pb, Cl, As, K, Fe, (Hg, Se, Zn, Sr, Rb, Mn, Cd, Mo) \\ S18 & S, Pb, Ca, Cl, As, K, Fe, (Se, Zn, Ti, Cu, Rb, Cd, Sr, Mn, Ba) \\ S19 & S, Pb, Ca, Cl, As, Hg, Fe, K, (Ti, Se, Zn, Cu, Rb, Sb, Mn, Sr) \\ S20 & Ca, S, Fe, Pb, K, Cl, As, I, (Hg, Mn, Zn, Sr, Ba, Cu, Se, Rb, Mo, Zr) \\ S21 & S, Pb, Cl, As, Ca, K, Fe, (Fe, Ca, Zn, Ti, Mn) \\ S22 & S, Pb, Cl, As, Ca, K, Fe, (Cd, Mn) \\ S23 & S, Pb, Cl, As, Ca, Hg, K, Fe, (Se, Zn, Cd, Rb, Mn) \\ S24 & S, Ca, Cl, Pb, K, Fe, As, (Hg, Mn, Se, Cu, Sb, Zn, Sr, Rb) \\ S25 & S, Pb, Cl, As, Ca, Hg, K, Fe, (Ti, Se, Cd, Zn, Mn, Ag) \\ S26 & S, Pb, Ca, Cl, K, As, Fe, Sb, Ti, (Zn, Ba, Se, Cr, Cd, Mn, Sr) \\ S27 & S, Ca, Pb, Cl, Fe, As, K, (Sb, Hg, Ti, Se, Mn, Zn, Cu, Sr, Rb, Cd, Mo) \\ S28 & Ca, S, Pb, K, Cl, Fe, As, (Zn, Sr, Mn, Cu, Se, Ba, Mo, Rb) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: X-ray fluorescence (XRF) elemental composition. Minor or trace elements reported in brackets. It is worth noting that Hg and Fe were not detected in the composition of point S22. This can be justified taking into account its whitish coloration, presumably based on white lead. Blackish/brown areas, as well as grayish areas (S11, S12, S14, S16, S17, S18, S20), are characterized by high-intensity peaks associated to Fe and Ca. This suggests the use by the artist of a red/brown ochre mixed with some white/red lead, together with a carbon-based black pigment, whose key-element cannot be directly identified by XRF due to the low atomic number, like charcoal and/or black bone (C + Ca\({}_{3}\)(PO\({}_{4}\))\({}_{2}\)). In the case of the light blue areas of the painting (S15, S21), the elemental composition obtained does not reveal any chromophore element that would allow the suggestion of a specific blue pigmenting agent of mineral provenance. Hence, the possible application of  
Figure 3: XRF spectra collected on the red area from [PERSON]’s cloak (S1, (**a**)); the green area from [PERSON]’s cloak (S4, (**b**)); the flesh-toned area from [PERSON]’s cheek (S10, (**c**)); the grayish-white area from the cloud under [PERSON]’s sandal (S12, (**d**)); the yellow-orange area from [PERSON]’s cloak (S13, (**e**)); the light blue area from the cerulean shades under the angel’s feet (S15, (**f**)); the blackish-brown area from [PERSON]’s hair (S20, (**g**)); and the left side of the canvas, at the bottom (S28, (**h**)). an organic-based blue pigment, most likely of plant origin, can be reasonably hypothesized. Unfortunately, as in the case of black colorations, no further suggestions can be proposed, due to the low atomic number of the corresponding elements.