Sources of Vermilion Collected from Ancient Japanese Tombs Determined by the Measurements of Lead Isotopes

Archaeological finds from ancient tombs provide very important information about the ancient world. Vermilion (mercury sulfide, HgS) has often been found in grave burialsites, which was used not only to preserve dead bodies, but also to represent the authority of the buried persons. It is considered that the origin of burial vermilion may reveal information about the culture, civilization, political status and so forth in an ancient society. To elucidate the origin of burial vermilion, we have been analyzing the lead isotope ratios in natural ore (cinnabar ore) samples from several mines (Japan: Nara, Mie and Tokushima prefectures. China: Guizhou, Hunan and Shaanxi) and burial vermilion from several ancient Japanese burial mounds built in the 2nd to 4th centuries for a comparison. For isotopic measurements of lead, we employed TIMS (thermal ionization mass spectrometry) and MC-ICP-MS (high-resolution ICP-MS equipped with a multi-collector). The lead isotopes in cinnabar ore exhibited clear local characteristics, and the origin of the cinnabar ore could be distinguished from the lead isotope compositions. Furthermore, it was deduced that three of the vermilion samples in ancient tombs built around the 4th century originated from the Kinki region, and that the vermilion sample from the Ohburo-minami remains originated from Hunan or Guizhou. For two samples (Nishidani and Tatetsuki ancient tombs), the origin was unclear. However, the lead isotope compositions imply that they may have originated from north-east China. The results of this study show that isotopic measurements of lead can be a powerful tool to distinguish the sources of vermilion from remains. We will additionally perform systematic isotopic analyses of lead for several cinnabar ore samples in order to establish a distribution map of lead isotopes, and also measure the lead isotopes for vermilion from other ancient tombs to determine the source of vermilion.