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Chemical Analysis of Starch-Like Mineral Crystals to Eliminate Misidentification in Ancient Residue Research



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.