## 4 Results and Discussion
### Ion Chromatography Analysis  
Ion chromatography (IC) analyses were performed on both the SP1 and SP2 argillite samples. Significantly, the concentration of soluble salts in both samples (Table 2) does not suggest salt-induced deterioration as a significant decay pathway [66; 67]. Sulfate (SO42-), commonly associated with salt crystallization damage and gypsum formation, was below the detection limit in both cases. Similarly, fluoride (F\({}^{-}\)) and nitrite (NO2-) were absent, indicating minimal influence from anthropogenic pollution sources. Although SP2 exhibited a higher overall ionic load--particularly with respect to calcium (5763.5 ppb), potassium (915.5 ppb), and sodium (213.8 ppb)--these values may reflect the original geochemical signature of the bedrock. Such findings may arise from the mineralogical composition and subsurface geochemical processes, rather than surface weathering. The presence of both carbonate (CO32-, 72.6 ppb) and bicarbonate (HCO3-, 125.1 ppb) in SP2 contrasts with SP1, which exhibited only bicarbonate (HCO3-, 179.6 ppb), suggesting leaching or transformation of carbonate phases during prolonged burial for the latter. This divergence is also mirrored in the pH values of the two samples (SP1: 7.8; SP2: 9.38), further indicating that SP1's burial context may have contributed to slight acidification. Chloride (Cl-), another salt of potential concern in crystallization-induced weathering (e.g., from marine aerosols), was present in moderate concentrations (i.e., SP1: 150.2 ppb; SP2: 208.3 ppb), albeit well below the thresholds typically associated with aggressive decay phenomena. Nitrate (NO3-) and phosphate (PO43-), likely introduced via soil interaction or biological activity, were also detected at comparably low levels in both samples. These findings strongly support the conclusion that salt weathering is not the dominant degradation process affecting the argillite stones at the Sanctuary of Apollo. This is consistent with field observations, which indicate that physical weathering--rather than salt-driven decay--is the prevalent deterioration mechanism. Of particular relevance, SP1 was derived from a monument that remained buried for centuries before excavation, a condition that could have mitigated its exposure to environmental salts but may simultaneously have fostered other weathering dynamics. In general, the deterioration of lithic materials is often closely associated with the mobilization of soluble salts, typically produced by acid-induced transformation of primary mineral phases [68]. Such acids may originate from atmospheric pollution, infiltrating water, or acidic soils. Once formed, these salts undergo repeated cycles of dissolution and crystallization in response to environmental fluctuations in temperature and relative humidity. The resulting volumetric changes exert mechanical stress on the stone's pore structure, leading to microfracturing and facilitating the penetration of reactive agents. Over time, this feedback loop may result in significant structural degradation, particularly if the stone's cementitious matrix becomes chemically altered or dissolved. The loss of this \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Sample** & **pH** & **CO32-** & **HCO3-** & **F**– & **Cl-** & **NO2-** & **NO3-** & **PO43-** & **SO42-** & **Na*** & **NH4+** & **K+** & **Ca2+** & **Mg2+** \\ \hline
**SP1** & 7.8 \(\pm\) & 0 & 179.6 \(\pm\) 3.2 & \textless\(\pm\)LD & \begin{tabular}{c} 150.2 \\ \(\pm\) 2.8 \\ \end{tabular} & \textless\(\pm\)LD & \begin{tabular}{c} \textless\(\pm\)LD \\ 1.9 \\ \end{tabular} & \textless\(\pm\)LD & \begin{tabular}{c} \textless\(\pm\)LD \\ 1.9 \\ \end{tabular} & \textless\(\pm\)LD & \begin{tabular}{c} \textless\(\pm\)LD \\ 2.1 \\ \end{tabular} & \textless\(\pm\)LD & \
\begin{tabular}{c} \textless\(\pm\)LD \\ 1.1 \\ \end{tabular} & \textless\(\pm\)LD &
\begin{tabular}{c} \textless\(\pm\)LD \\ 213.8 \\ \end{tabular} & \textless\(\pm\)12.7 & \(\pm\)84.6 & \(\pm\)2.6 \\ \hline \hline \end{tabular}
\end{table}