X-ray Diffraction Analysis of Clay Particles in Ancient Baekje Black Pottery: Indicator of the Firing Parameters

Abstract

An X-ray diffraction (XRD) analysis was conducted after separating clay particles from three shards, to analyze the production technique of black pottery excavated from a historical site of ancient Baekje in Seoul, South Korea. Through the analysis, clay minerals and iron oxides that were not recognized in the XRD patterns of the bulk powder samples were identified. A pottery type with a blackened portion from the surface to the margin and the core was estimated to have been produced in a reduction firing environment of less than 900 °C, by detecting illite and magnetite. As for the other blackened pottery, a brown soil color remained in the core, and the presence of illite and kaolin was confirmed. In addition, while magnetite was detected on the black surface and margin, hematite was detected in the core. These results confirm that this type of blackened pottery was produced through reduction firing at a temperature below 550 °C. In particular, the results indicate that there is a new category of pottery, produced by firing at lower temperatures in a reduction atmosphere, previously not reported by research on ancient Baekje black pottery, which could be discovered due to its specific clay particles.