In this context, Laser-Induced Breakdown Spectroscopy (LIBS) has gained increased attention over the past two decades [19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33]. Its appeal in the analysis of Cultural Heritage materials lies in the minimal sample preparation, broad elemental coverage across the periodic table, and flexibility regarding sample geometry or size [34; 35; 36; 37]. Moreover, laser pulses can effectively remove dust coatings, thus facilitating the investigation of weathering layers, either by exposing them directly or through layer-by-layer analysis [38; 39]. Despite these advantages, LIBS faces several methodological challenges, most notably the matrix effect, which can cause variability in ablation and emission processes depending on the material. In the context of LIBS applied to archaeological artifacts, the matrix effect refers to the influence exerted by the sample's chemical composition and physico-structural properties on laser ablation, plasma formation, and spectral emission processes. Variations in the matrix (e.g., silica-based, calcareous), even at constant elemental concentrations, can significantly alter the intensity and shape of spectral lines, thus compromising the accuracy of quantitative analysis. This effect is particularly relevant in archaeological materials, which are often heterogeneous and altered, and requires compensation strategies such as matrix-matched calibration, the use of internal standards, or multivariate data processing (see, e.g., [40; 41]). LIBS spectra are also complex, with overlapping emission lines from many elements, making untargeted analysis difficult. Additionally, being a laser-based technique, temperature plays a critical role; the optimal operating range is around 30 \({}^{\circ}\)C, which requires careful temperature control during in-situ use. Thus, while h-LIBS is well-suited for qualitative analysis, achieving accurate quantitative results is more complex. As with other analytical techniques, reliable quantitative LIBS analysis requires proper calibration, typically achieved through calibration curves generated using established standards [42; 43; 44; 45; 46; 47; 48]. Successful quantitative LIBS applications using bench-top instruments have been reported in Cultural Heritage studies [49; 50; 51; 52; 53; 54]. For instance, [PERSON] et al. quantified Fe, Ca, and Mg in archaeological ceramics, using specific calibration standards and selected emission lines [55], while [PERSON] et al. examined prehistoric bronze artifacts from a Bulgarian site, applying both surface and cross-section analysis to determine Sn and Pb concentrations [56]. However, these studies rely on univariate calibration approaches, which utilize limited spectral information and are more susceptible to fluctuations in plasma conditions. To overcome these limitations, multivariate calibration methods, particularly those based on chemometrics, are increasingly adopted. For instance, [PERSON] et al. used Double Spectral Correction-Partial Least Squares (DSC-PLS) to determine carbon content in powdered coal with bench-top LIBS [57]. [PERSON] et al. [58] combined LIBS and plasma-induced luminescence hyperspectral imaging using a data fusion strategy to analyze heterogeneous kyanite mineral samples, applying Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) on compressed datasets to extract chemical features. [PERSON] et al. [47] employed multivariate regression to analyze geochemical standards obtaining quantitative information about major, minor, and trace elements. An alternative strategy for quantitative analysis without external calibration is provided by Calibration Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) [59; 60; 61], which assumes stoichiometric ablation, local thermodynamic equilibrium (LTE), and optically  
These three samples, together with the obsidian fragment (TY_MA_51), were recovered during the August 1970 excavation campaign in the _Cercadenari_ area, specifically from the _decumanus_, quadrants P19-20-21, layer II.