Specialized production of coins in early China: a study of coin-casting ceramic molds unearthed from mints in the Qi state of the Eastern Zhou period

Abstract

Bronze coins, starting to be used in the Eastern Zhou period (770 − 221 BC) in China, were produced in ceramic piece molds, a predominant technique for bronze casting in the Chinese Bronze Age. This study examined coin-casting molds unearthed at the Ju Mint and the Linzi Mint in the Qi state, dating to the Eastern Zhou period, to investigate the specialization of early Chinese coin production. The material characteristics, repair and reuse were examined using analytical techniques including SEM-EDS, DIL, FTIR, p-XRF, XRD and specific gravity balance. A simulation experiment was conducted to rebuild the mold production process. The dimensions of both the molds and their cavities were measured. The results showed that the material characteristics of these coin-casting molds significantly differ from those of other types of bronze-casting molds. The coin-casting mold was most likely modified from the conventional bronze-casting molds to increase their lifespan in coin-casting. Moreover, the high degree of uniformity in the material characteristics, the dimensions of molds as well as the cavities, on one hand, indicates a standardization of coin production under unified government control; on the other hand, the differences in minor and trace elements between the coin-casting molds from the two mints suggest that the molds may have been produced independently at each mint using local materials. This paper offers a novel perspective in understanding China’s early monetary system and technical history.