## 3 Results and Interpretation
### Chemical Composition and Variations
#### 3.3.2 Chemical Variation
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline
**No.** & **SiO2** & **Al2O3** & **Fe2O3** & **CaO** & **MgO** & **Na2O** & **K2O** & **CuO** & **MnO** & **PbO** & **SnO2** & **TiO2** & **SO3** & **Total** \\ \hline a1 & 68.98 & 19.42 & 4.94 & 1.44 & 1.40 & 0.47 & 2.30 & 0.00 & 0.00 & 0.00 & 0.82 & 0.00 & 99.77 \\ a2 & 68.38 & 2.41 & 1.37 & 6.48 & 0.79 & 19.05 & 0.34 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 98.82 \\ a3 & 69.00 & 2.25 & 1.22 & 6.52 & 0.64 & 18.94 & 0.34 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 98.91 \\ a4 & 84.61 & 3.07 & 1.53 & 7.39 & 0.80 & 1.16 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 98.56 \\ a5 & 84.18 & 3.04 & 1.34 & 7.76 & 0.89 & 1.04 & 0.32 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 98.57 \\ \hline b1 & 73.97 & 4.50 & 1.49 & 1.76 & 0.80 & 11.82 & 1.21 & 2.72 & 0.00 & 0.00 & 0.00 & 0.70 & 0.38 & 99.35 \\ b2 & 72.90 & 4.20 & 0.96 & 2.03 & 0.58 & 11.96 & 1.16 & 4.77 & 0.00 & 0.00 & 0.00 & 0.75 & 0.00 & 99.31 \\ b3 & 73.27 & 4.57 & 1.06 & 1.66 & 0.97 & 12.32 & 1.19 & 3.91 & 0.00 & 0.00 & 0.00 & 0.44 & 0.00 & 99.39 \\ b4 & 73.47 & 4.46 & 1.49 & 1.82 & 0.63 & 11.94 & 1.41 & 3.33 & 0.00 & 0.00 & 0.00 & 0.36 & 0.40 & 99.31 \\ \hline c1 & 35.13 & 7.44 & 2.69 & 0.00 & 0.00 & 15.24 & 0.00 & 0.00 & 0.00 & 7.55 & 31.34 & 0.00 & 0.00 & 99.39 \\ c2 & 41.20 & 7.78 & 0.89 & 0.00 & 0.46 & 12.45 & 0.00 & 0.00 & 0.00 & 30.07 & 6.64 & 0.00 & 0.00 & 99.49 \\ c3 & 34.89 & 4.96 & 0.00 & 0.00 & 0.00 & 13.01 & 0.00 & 0.00 & 0.00 & 37.50 & 9.64 & 0.00 & 0.00 & 100.00 \\ \hline d1 & 76.20 & 1.12 & 0.40 & 1.31 & 0.51 & 0.00 & 17.75 & 1.80 & 0.91 & 0.00 & 0.00 & 0.00 & 0.00 & 100.00 \\ d2 & 75.72 & 1.23 & 0.60 & 1.50 & 0.39 & 0.00 & 17.61 & 1.90 & 1.05 & 0.00 & 0.00 & 0.00 & 0.00 & 100.00 \\ d3 & 84.86 & 1.35 & 1.18 & 1.81 & 0.66 & 0.00 & 6.58 & 2.37 & 1.20 & 0.00 & 0.00 & 0.00 & 0.00 & 100.01 \\ d4 & 89.01 & 3.77 & 1.12 & 1.39 & 0.66 & 0.00 & 0.40 & 2.36 & 0.93 & 0.00 & 0.00 & 0.00 & 0.00 & 99.64 \\ \hline e1 & 2.05 & 0.00 & 97.69 & 0.26 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 100.00 \\ e2 & 43.31 & 5.82 & 0.83 & 0.92 & 0.93 & 0.00 & 0.92 & 44.16 & 0.00 & 0.00 & 0.00 & 0.23 & 2.41 & 99.53 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Chemical compositions (wt.%) of glass bead samples. The numbers are the same as those used in Figure 5.  
The results of the SEM-EDS analysis of the weathered and non-weathered surfaces of the blue-green glass beads from tomb No. 11 showed differences in the composition and concentrations of chemicals (Figure 5d). Small differences in the SiO\({}_{2}\) concentration were identified: 75.72 to 76.20 wt.% on the non-weathered surfaces, and 84.86 to 89.01 wt.% on the weathered surfaces (Table 3). The greatest difference identified was the K\({}_{2}\)O concentration. The concentration of K\({}_{2}\)O on non-weathered surfaces was 17.61 to 17.75 wt.%, but the concentration on weathered surfaces was only 0.40 to 6.58 wt.%, depending on the weathering conditions (Figure 5d). This may be because alkali elements have a high level of liquidity and can be easily dehydrated or elviuated from weathering. In addition, as the formula weight of the hydrogen ions substituted with potassium ions from the hydration process is lower, the weathered surfaces were darker in color than the non-weathered surfaces [20]. The surfaces of the brown glass beads from tomb No. 12 had an increased concentration of crystalized substances, and black and white impurities, as observed on other glass beads (Figure 5e). The results of the SEM-EDS showed that 97.69 wt.% of the beads was Fe\({}_{2}\)O\({}_{3}\), with small amounts of SiO\({}_{2}\) and CaO (Table 3). As the base material of glass naturally contains some Fe, glass is a light-blue color if there are no coloring materials added [21; 22; 23]. However, Fe turns yellow or reddish-brown in color following oxidization. It is estimated that Fe was added to the glass for colorization, as Fe was included within glass in the crystal form.