CHEMICAL ANALYSIS OF STARCH-LIKE MINERAL CRYSTALS TO ELIMINATE MISIDENTIFICATION IN ANCIENT RESIDUE RESEARCH*

摘要

To clarify issues involved in problematic identification of ancient starch granules, we investigated suspected granules found in residues from a Neolithic grinding stone in north-east China. The chemical compositions of suspected granules and modern starch granules were tested via SEM-EDS. The results show that the elemental composition of the suspected granules mainly comprises O, S and Ca, which is similar to the composition of calcium sulphate, but quite different from that of real starch granules, which show high levels of C and O, with very low level of other elements. The findings in this study act as a warning that tiny mineral granules may be misidentified as starch, and also indicate that the method of SEM- EDS can be useful to confirm the nature of suspected granules in ancient starch analysis.