## 3 Results and Interpretation
### Chemical Composition and Variations  
#### 3.3.1 Classification  
A SEM-EDS analysis was conducted to identify the chemical compositions of the glass beads (Table 2). Surface analyses were performed by dividing the glass beads into three to eight areas based on size and form, and the results of the analysis are shown as means. The major elements of glass are silica oxides, with oxidized alkali added to lower the melting temperature and make processing easier (Figure 3). The alkali elements are called fluxes, and these include Na\({}_{2}\)O and K\({}_{2}\)O [3; 5; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18]. To identify the compositions of the glass beads excavated from the Suchonri site, the relationship between the concentrations of Na\({}_{2}\)O and K\({}_{2}\)O was graphed. The graph shows that all samples, aside from the fragments of blue-green glass beads from tomb No. 11, were soda glass with large amounts of Na\({}_{2}\)O, regardless of their color. The fragments of blue-green glass beads from tomb No. 11 had more weathering at the edges, compared with the other glass beads, and it was possible to observe brown weathering boundaries under a microscope. This is because potash glass has chemical properties that make it more vulnerable to weathering than soda glass [19; 20]. Stabilizers, which increase durability and maintain chemical stability, are added to glass. Based on the use of CaO and Al\({}_{2}\)O\({}_{3}\) (5 wt.%) as stabilizers, the glass may be classified as LCA (low CaO, Al\({}_{2}\)O\({}_{3}\)), LCHA (low CaO, high Al\({}_{2}\)O\({}_{3}\)), HCLA (high CaO, low Al\({}_{2}\)O\({}_{3}\)), or HCA (high CaO, Al\({}_{2}\)O\({}_{3}\)). In addition, LCA glass can be divided into LCA-A (low CaO \(<\)  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Compounds** & **S8-G-Blue** & \begin{tabular}{c} **S11-G-** \\ **Brown** \\ \end{tabular}  & \begin{tabular}{c} **S11-G-** \\ **Green** \\ \end{tabular}  & \begin{tabular}{c} **S11-G-** \\ **Blue-green** \\ \end{tabular}  & \begin{tabular}{c} **S12-G-** \\ **Brown** \\ \end{tabular}  & \begin{tabular}{c} **S18-G-** \\ **Lightgreen** \\ \end{tabular}  & \ \begin{tabular}{c} **S18-G-** \\ **Brown** \\ \end{tabular}  & \begin{tabular}{c} **S18-G-** \\ **Green** \\ \end{tabular}  \\ \hline SiO\({}_{2}\) & 68.61 & 70.59 & 60.37 & 78.63 & 66.73 & 63.49 & 63.91 & 68.89 \\ \hline Al\({}_{2}\)O\({}_{3}\) & 2.40 & 4.28 & 8.70 & 1.24 & 8.32 & 11.54 & 10.49 & 6.81 \\ \hline Fe\({}_{2}\)O\({}_{3}\) & 1.24 & 1.35 & 1.09 & 0.63 & 2.06 & 0.74 & 1.82 & 2.35 \\ \hline CaO & 6.29 & 1.78 & 2.74 & 1.62 & 1.91 & 1.53 & 2.90 & 1.54 \\ \hline MgO & 0.71 & 0.80 & 0.09 & 0.63 & 0.82 & 0.05 & 0.39 & 0.13 \\ \hline Na\({}_{2}\)O & 19.13 & 15.22 & 19.31 & 0.00 & 14.79 & 17.49 & 12.95 & 12.94 \\ \hline K\({}_{2}\)O & 0.32 & 1.26 & 1.73 & 14.06 & 1.79 & 3.05 & 1.14 & 1.90 \\ \hline CuO & 0.00 & 3.11 & 0.95 & 2.09 & 1.93 & 0.54 & 2.05 & 0.85 \\ \hline MnO & 0.00 & 0.00 & 0.00 & 1.12 & 0.00 & 0.00 & 0.00 & 0.00 \\ \hline PbO & 0.00 & 0.00 & 4.18 & 0.00 & 0.00 & 0.00 & 2.80 & 2.43 \\ \hline TiO\({}_{2}\) & 0.00 & 0.65 & 0.39 & 0.00 & 0.86 & 0.55 & 0.90 & 1.73 \\ \hline SO\({}_{3}\) & 0.13 & 0.34 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 \\ \hline Total & 98.83 Al\({}_{2}\)O\({}_{3}\)), which has large amounts of Al\({}_{2}\)O\({}_{3}\), and LCA-B (low CaO > Al\({}_{2}\)O\({}_{3}\)) which has large amounts of CaO [5; 16; 17; 20]. The glass beads excavated from the Suchonri site were classified based on the composition of their stabilizers (Figure 4). The results show that the blue-green glass beads from tomb No. 11, which are potash glass, were classified as LCA, and were closer to LCA-B due to having a relatively large concentration of CaO, in contrast to rather than LCA-A glass, which has a relatively large concentration of Al\({}_{2}\)O\({}_{3}\) (Figure 4a). Soda glass was identified in LCA, LCHA, and HCLA areas, aside from HCA.