## 3 Sampling and Analytical Methods  
The female bust was studied using laboratory investigations after obtaining some microsamples of the material to be analyzed. Sampling (Figure 3) was performed with the assistance of the restorers acting on behalf of the Superintendency of Archaeology, Fine Arts, and Landscape for the metropolitan city of Reggio Calabria and Vibo Valentia (SABAP) in order to collect representative fragments useful for providing a correct interpretation of the data. Specifically, five microsamples were chipped-off from the base of the bust and at the front nearby the breasts, using suitable stainless-steel tools (lancets and small chisels) to establish the composition of the raw materials and the possible presence of alteration products. Diagnostic investigations of the selected microfragments were carried out using different and complementary analytical methodologies also chosen based on the amount of samples available. Specifically:  
Polarizing optical microscopy (OM) to define the mineralogical and textural features of the constituent material (i.e., marble) of the bust (sample BF_tl_1). Thin section observation was carried out through a Primotech 40 (Primotech Zeiss) microscope coupled with a digital camera to capture images. The analyzed textural features included the grain boundary shape (GBS), the shape preferred orientation (SPO), and the maximum grain size (MGS) of calcite and/or dolomite crystals, as these features are dependent on the metamorphic evolution of the protoolith. X-ray diffractometry (XRD) was performed using a Bruker D8 Advance X-ray diffractometer (Bruker, Karlsruhe, Germany) and Bragg-Brentano geometry, with a copper sealed tube X-ray source producing Cu k radiation (wavelength of 1.5406 A) from a generator operating at 40 kV and 40 mA. The diffracted X-rays were recorded on a scintillation  
Figure 3: Representative images of sampling points (**A**,**B**) with details of alteration products and constituent material taken from the bust (**C**–**G**). counter detector located behind a set of long Soller slits/parallel foils. Scans were collected in the range of 3-65\({}^{\circ}\) 20, using a step size of 0.014\({}^{\circ}\) 20 and a step counting time of 0.2 s. EVA software (DIFFRACplus EVA version 11.0. rev. 0) was used to identify mineral phases in samples BF_tl_1 and BF_tl_3 by comparing experimental patterns with 2005 PDF2 reference patterns. Mass spectrometry was used for the measurement of carbon and oxygen stable isotopes (\(\delta^{13}\)C, \(\delta^{18}\)O) of sample BF_tl_1. Analysis was performed at the mass spectrometry laboratory of the Department of Earth and Marine Sciences of the University of Palermo (Palermo, Italy) using an automated continuous flow carbonate preparation GasBench II device [26] and a ThermoElectron Delta Plus XP mass spectrometer. A small amount of powder was obtained using a micromill or with a small handheld 2 mm drill. The powders were heated at 400 \({}^{\circ}\)C to remove organic components and later subjected to acidification at 50 \({}^{\circ}\)C. Samples were calibrated to Vienna Pee Dee Bellemite (V-PDB) using an internal standard (Carrara Marble with \(\delta^{18}\)O = \(-\)2.43% vs. V-PDB and \(\delta^{13}\)C = 2.43% vs. V-PDB) and NBS19. Standard deviations of oxygen and carbon isotope measures were estimated as 0.08 and 0.1%, respectively, based on \(\sim\)100 repeated samples. All isotope data were reported per mil (%) relative to the V-PDB standard. A scanning electron microscope, ultrahigh resolution SEM (UHR-SEM) ZEISS Cross-Beam 350 equipment, coupled with a spectrometer EDS/EDAX OCTANE Elite Plus--Silicon drift type, was used to obtain information about morphology and chemical composition (in terms of major elements) of samples BF_tl_4 and BF_tl_5. Instrumental conditions set for EDS analysis were HV: 15 keV and probe current: 100 pA.  
As far as FT-IR investigation is concerned, the used spectrophotometer was a Perkin Elmer Spectrum 100, equipped with an attenuated total reflectance (ATR) accessory.