## 4 Conclusions  
X-ray spectroscopic characterization of the ancient burial potteries produced at Ban Muang Bua archaeological site, Roi Et province (northeastern Thailand) was achieved. The amounts of Si, Al, and Fe in core tended to be larger, approximately the same, and lower, respectively, than outer and inner layers. SEM micrographs showed morphologies of composites in the core that contained irregular plate-like particles with a wide range of size distribution, and the dense outer and inner layers of glazes. The results corresponded to SR XTM which revealed high porosity of the core. The low contents of Ca and K for both outer and inner layers indicated low firing temperatures of samples (\(\sim\)600-900 \({}^{\circ}\)C) in open-air kilns. These results implied the production technology of ancient pottery. The raw materials of pottery in our present and previous works were originated from the same source. The two pottery types might be produced with different kilns and amounts of raw materials. The raw materials were sandy soil derived from marine sands, clays, and salt deposits that were mostly iron-rich-kaolin clay. This archaeological evidence reflected iron smelting and salt manufacturing in this area. Conceptualization, K.W.-i., C.B., and P.D. ; methodology, K.W.-i. and P.D. ; software, C.T. and P.P. ; validation, C.B., K.W.-i., P.P., U.T., and P.D. ; formal analysis, N.N., C.T., P. P., and P.D. ; investigation, C.B., K.W.-i., N.N., P.P., U.T., and P.D. ; resources, K.W.-i. and N.N. ; data curation, C.B., K.W.-i., and P.D. ; writing-original draft preparation, K.W.-i. and P.D. ; writing-review and editing, C.B., K.W.-i., P.P., U.T., and P.D. ; visualization, N.N., P.P., and P.D. ; supervision, K.W.-i. and C.B. ; project administration, K.W.-i. ; funding acquisition, K.W.-i., C.B. and U.T. All authors have read and agreed to publish version of the manuscript. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{8}{c}{**Elemental Composition (wt\%)**} \\ \cline{2-13}  & **C** & **O** & **Na** & **Mg** & **Al** & **Si** & **S** & **P** & **Cl** & **K** & **Ca** & **Ti** & **Fe** \\ \hline Outer layer & & & & & & & & & & & & & & \\ Previous & 4.66 & 52.14 & \textless{}0.17 & \textless{}0.23 & 5.00 & 35.19 & \textless{}0.10 & \textless{}1.04 & \textless{}0.10 & 0.29 & \textless{}0.41 & \textless{}0.34 & 1.01 \\ Present & 3.64 & 52.58 & \textless{}0.14 & \textless{}0.16 & 6.13 & 33.23 & \textless{}1.11 & \textless{}0.87 & \textless{}0.10 & 0.46 & 0.88 & 0.38 & 1.82 \\ Core & & 3.99 & 52.19 & 0.12 & \textless{}0.10 & 5.68 & 35.05 & \textless{}0.10 & 1.04 & \textless{}0.10 & 0.30 & 0.44 & 0.33 & 1.15 \\ Previous & 2.35 & 51.79 & \textless{}0.14 & \textless{}0.12 & 6.15 & 36.05 & \textless{}0.10 & \textless{}0.41 & \textless{}0.10 & 0.47 & 0.60 & 0.36 & 1.17 \\ Inner layer & & & & & & & & & & & & & \\ Previous & 5.68 & 51.20 & \textless{}0.28 & \textless{}0.13 & 6.27 & 32.74 & \textless{}0.10 & 1.20 & \textless{}0.20 & 0.36 & 0.60 & 0.46 & 1.35 \\ Present & 7.85 & 49.42 & \textless{}0.16 & \textless{}0.14 & 5.66 & 33.34 & \textless{}0.10 & 0.51 & \textless{}0.11 & 0.48 & 0.71 & 0.36 & 1.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Comparison between average elemental compositions of Ban Muang Bua pottery in previous (Data from [20]) and present works. Adapted with permission from [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] (2019) (Malays. J. Microsc.) [20]. Figure 7: Tomographic images of MB051, MB055, MB056, and MB059 which provided visualization of internal structure (brown), and pore and crack (green). The length of scale bars located at the bottom right corner or top right corner of images is 100.00 \(\upmu\)m.  
**Funding:** This research is partly funded by the Faculty of Science (Department of Earth Science) at Kasetsart University and Center of Excellence in Materials Science and Technology (Chiang Mai University).