Micro-Raman spectroscopy of Shang oracle bone inscriptions

Abstract

Oracle bone inscriptions (OBI) refers to graphs engraved on scapulae and turtle shells as part of divination practice in Shang dynasty (ca. 1600–1050 BCE). Hundreds of thousands of oracle bones have been unearthed at Anyang, Henan, the last capital of Shang dynasty, during the last century. OBI represents not only the earliest known Chinese writing but also the oldest extant documents about Shang history. Here we employed a non-invasive micro-Raman spectroscopy to investigate the composition of pigments found in the grooves of OBI graphs on 48 pieces of shells and bones. Among the 86 graphs we analyzed, 37 contained cinnabar, 7 contained hematite, 3 contained both cinnabar and hematite, and 1 contained goethite. Another 37 graphs contained carbon black, and 1 contained graphite. The sensitivity of micro-Raman allows us to identify OBI coloration even if the color has faded and not visible. Thus, micro-Raman analysis would allow us to restore the original coloration pattern of OBI graphs as the Shang diviner applied three thousand years ago. The extensive use of red and black coloration for OBI is consistent with the dichotomy nature of the positive and negative charge as imposed by the diviners. The restoration of original coloration will be essential for relating the coloration with other divination parameters such as crack numerals, crack notations, and the content of OBI inscriptions. Such correlation will help us to understand the function of coloration and its role in Shang divination.