## 3 Results  
### Inorganic Pigment Analysis  
#### 3.1.1 OM Observation and SEM-EDX  
Figure 3 illustrates the optical and SEM cross-section images and elemental mappings. As the OM images show in Figure 3, all samples except #1 had relatively clear layers. Except for #1 and #4, clear gold could be observed in all samples. As mentioned above, most surfaces were coated with gold, and the colors of the layer beneath gold varied, include purplish red, orange, brown, blue, and white. The results of elemental analysis showed that Au (gold) was detected in all samples. In addition to Au, Ag (silver) was detected in sample #8. Ag was mixed with Au, whereby Au dominated in the elemental mapping; thus, Ag can be considered as an impurity in the gold. Although the golden color was not visually apparent in sample #1, it can be seen in the elemental distribution map that Au was scattered in Pb and Ca. This suggests that Au distributedin #1 was not in the form of foil but in the form of powder, mixed with a substance containing Pb and Ca. In #2, gold leaf with some Fe-containing red particles was identified in the upper layer, while characteristic elements such as Hg, Pb, and Ca were absent in the mordant layer. Sample #3 exhibited a thick red organic resinous layer beneath the gold foil, and, under the red organic layer, there was an orange layer with Pb. In #4, there were three red layers above the white ground, containing Pb + As, Ca + As, and Ca + Fe. Sample #5 had a distinct thick red layer on the upper gold layer, while a blue layer was beneath the gold foil. Sample #6 had no obvious element detected under the gold foil. Sample #7 presented a Pb-containing orange layer as mordant and a small number of red particles in the upper layer that also contained Pb. In #8, a red-black material was found in the upper layer, along with a dark-red layer and Pb concentrated orange layer under the foil. In #9, a thicker orange-red layer was visible in the upper layer where Pb and Ca were present. Sample #10 showed a thick red organic resinous layer beneath the gold foil, followed by an orange layer with Pb.  
Overall, no distinct foil overlay was observed on #6 and #10. Furthermore, #3, #7, #8, #9, and #10 were similar in structure, all having an orange-red layer coated with a dark-red resin layer, followed by gold leaf and a white layer containing Ca and S beneath.  
The BSE images of the cross-section shown in the second row of Figure 3 reveal the differences in atomic numbers; brighter areas indicate lower elements in the periodic table with a higher atomic number. As shown in Figure 3, the brightest area was represented by gold, while the dark areas are likely represented by organic compounds.  
In #6, only the lower layer of gold leaf was found to contain Ca and S. The red layer in the middle was not measured for the characteristic elements and may be an organic dye. The upper surface layer of gold foil in #2 was dominated by Fe and Si, while the lower purplish layer of gold foil contained Ca and S; no characteristic elements of any mineral pigments show this color. Therefore, the purplish layer was presumably made of some organic colorant mixed with gypsum. The upper red layer of gold foil in #5 contained only Ca and S, suggesting that the red color may have come from organic colorant. It is likely that dye mixed with gypsum was used in these samples. The bright blue beneath the gold layer in sample #5 may be lapis lazuli due to a lack of characteristic elements such as Cu (azurite) and Co (snalt, cobalt).