## 3 Results
### DSC/TG Characterisation  
To avoid ambiguity in the distinction of serpentine polymorphs, the M-17 and M-12 samples were also characterised by DSC/TG and TEM/EDS/SAED. It is worth mentioning that thermal analysis has been successfully employed in the distinction of serpentine minerals (chrysotile, lizardite, antigorite and polygonal serpentine) [14; 15; 16] that are otherwise subject to ambiguous characterisation by XRPD.  
The thermograms of the two samples were different (Figure 10a-d) due to the different phases present, besides chrysotile. The DSC curve, relative to the sample M-17, showed a shoulder effect at around 610 \({}^{\circ}\)C, which became a very evident peak at 614 \({}^{\circ}\)C in the DDSC curve (Figure 10a), which was related to chrysotile collapse [15]. This was also confirmed by the maximum loss rate peaks recorded on the DTG curve at 611 \({}^{\circ}\)C, ascribed to chrysotile dehydroxylation (Figure 10b). It is worth mentioning that the dehydroxylation temperature was taken to be the temperature of the maximum rate of weight loss. The very intense dehydroxylation effect (between 500 and 600 \({}^{\circ}\)C) that preceded the collapse of the chrysotile (Figure 10b) was related to the breakdown of the magnesite [14].  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **Raw before Laser Ablation as Detected by XRPD and SEM/EDS** & **After Laser Ablation Phases as Detected by XRPD and SEM/EDS** & **After Laser ADlation Phases as Detected by XRPD, DSC/TG, TEM/EDS/SAED** \\ \hline M-12 & Serpentine \textgreater{} clinochree \textgreater{} talc \textgreater{} dolomite & Dolomite \textgreater{} talc \textgreater{} chrysotile\textgreater{} lizardite \\ M-17 & Talc \textgreater{} serpentine \textgreater{} magnesite \textgreater{} dolomite & Magnesite \textgreater{} talc \textgreater{} chrysotile \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mineralogy of samples before (raw sample) and after laser ablation.  
Figure 7: XRPD of sample M-12, whole rock before ablation, where peaks of a serpentine phase (antigorite) and carbonate (dolomite) are preeminent, also containing some talc and chlorite.  
Figure 8: Study under the microscope of powder obtained after laser ablation. (**a**) Mask retrieved from the laser equipment; (**b**) mask under the microscope; (**c**) clean mask under the microscope—the original texture of the mask is shown here; (**d**) mask with the retained powder after laser ablation—only a mass of talc is seen in this picture.  
Figure 9: Diffractogram of sample M-17 before (raw) and after laser ablation; the black square in the figure indicates the enlarged diffractogram area underneath, where the main reflection of the serpentine mineral phase is clearly visible.  
Figure 10: Thermal analysis of M-17 and M-12 samples: (**a**) sample M-17, blue solid line DSC, blue dashed line DDSC; (**b**) sample M-17, green solid line TG, green dotted line DTG; (**c**) sample M-12, blue solid line DSC, blue dashed line DDSC; (**d**) sample M-12, green solid line TG, green dotted line DTG.  
DTG on sample M-12 showed one very intense maximum loss rate at 733 \({}^{\circ}\)C, ascribed to the liberation of CO\({}_{2}\) relative to the dolomite collapse, and a weak shoulder at 603 \({}^{\circ}\)C, which was ascribed to chrysotile breakdown (see Figure 10d). The weak signal at around 600 \({}^{\circ}\)C on the DDSC curve confirms the presence of chrysotile (serpentine polymorph) (Figure 10c). Moreover, at 663 \({}^{\circ}\)C, a signal was clearly recorded on the DDSC curve due to lizardite breakdown. In both thermograms, the low intensity of the peaks that identify chrysotile is related to the low quantity present in HEPA filters. Moreover, in both thermograms (Figure 10b,d), the initial weight loss observed up to 120 \({}^{\circ}\)C on the TG curves was attributed to the release of water adsorbed at the sample surface and on the DSC curve (Figure 10a,c), and the exothermic peaks were related to the crystallisation of phases (e.g., forsterite) after the breakdown events [15; 16].