## 4 Results and Discussion
### Mineralogical-Petrographic and Geochemical Characterization of the Bust  
Sample BF_tl_1 from the hollow under the base of the bust (Figure 3; Table 1) was subjected to minero-petrographic and geochemical studies to characterize the material and hypothesize its origin. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample Id** & **Brief Description** & **Employed Techniques** \\ \hline BF\_tl\_1 & \begin{tabular}{c} White marble microfragment from the \\ hollow under the base of the bust \\ \end{tabular} & OM; XRD; \(\delta^{13}\)C and \(\delta^{18}\)O isotopes \\ \hline BF\_tl\_2 & \
\begin{tabular}{c} Whitish material from the hollow under the \\ base of the bust superimposed on the \\ constituent marble of the artifact \\ \end{tabular} & FT-IR \\ \hline BF\_tl\_3 & Reddish material from the left breast & FT-IR; XRD \\ \hline BF\_tl\_4 & Reddish material from the right breast & FT-IR; SEM-EDX \\ \hline BF\_tl\_5 &
\begin{tabular}{c} Incoherent whitish material superimposed \\ onto BF\_tl\_4 \\ \end{tabular} & FT-IR; SEM-EDX \\ \hline \hline \end{tabular}
\end{table} 
Table 1: List of the examined microsamples, brief descriptions, and employed analytical techniques. Polarizing Optical Microscopy, X-ray Diffraction, and Isotopic Analysis  
Sample BF_tl_1 is a white marble characterized by a fine grain size (MGS \(<\) 1 mm) and a homeoblastic texture (Ho) with small-to-tiny grains, forming triple points in places. The grain size ranges from 0.1 mm to 0.43 mm (MGS), often with clear cleavage traces, while the grain boundary shape (GBS) varies from curved to straight. The shape preferred orientation (SPO) of the grains was not observed (Figure 4). As regards the MGS of crystals in the examined marble sample, the values are less than 0.4 mm. The comparison with data from the literature [29; 30; 31; 32; 33] reported in the diagram of Figure 5 shows that sample BF_tl_1 has the typical MGS of Carrara, Dokymeion (Afyon), Aphrodisias, Goktepe, Penteli, and Hymettos. The other petrographic parameters investigated (GBS and SPO) were also compared with the literature data for ancient quarries in the Mediterranean region [32; 34; 35; 36], further confirming the above considerations drawn using the MGS ranges (Figure 5). It is noteworthy to point out that the more recent petrographic studies on fine-grained white marbles used in antiquity [2; 37] have shown that although marbles may exhibit a unique set of features, their fabrics and grain size are more variable than initially suggested, and several types of fine-grained white marbles can be confused with each other. In particular, there are very close petrographic similarities between Carrara and Goktepe marble. To overcome these ambiguities, several geochemical analytical methods are strongly suggested as key criteria to distinguish them [38; 39; 40], with particular attention to the recent and improved methodology proposed by [4] and from the new approach of [1]. Figure 4: Representative photomicrographs (cross-polarized light) showing textural features of the marble fragment. Central (**A**) and lateral (**B**) portion of the section with evidence of homeoblastic texture and triple points. Figure 5: MGS diagram for marbles of the Mediterranean area. Comparison between literature data and sample BF_tl_1. Concerning the mineralogical composition, the XRD analysis revealed that the sample is a pure calcite marble. The mineralogical composition is a further discriminating parameter regarding the origin of ancient white marble items [1; 30; 34; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53; 54; 55; 56; 57; 58; 59; 60; 61; 62; 63]. The determination of the oxygen and carbon isotopic ratios (\(\delta^{13}\)C and \(\delta^{18}\)O) was used for the first time by [PERSON] and [PERSON] [44] for the attribution of the origin of Mediterranean white marbles.