A testimony of prehistoric tasks: Diagnostic residues on stone tool working edges

This paper describes a scanning electron microscope study of the edges of experimentally used and prehistoric stone tools that exhibited microwear polishes when observed using optical microscopy. The S.E.M. revealed areas of the tool edges with a ‘dissolved’ appearance, associated with firmly adhering microscopic mineral residues from plant and animal tissues. Mechanisms are proposed to explain these observations. Residue materials on the archaeological and experimental tools were found to be composed principally of silicium or calcium, and include grass phytoliths, crystalline materials from wood cells, and fragments of silicified wood cells, as well as bone mineral and other animal tissues. Most of the mineral residues were quite characteristic of the cells from which they came, often replicating parts of cellular structures. The author uses comparative morphological studies of the structure and mineral components of appropriate biological materials to demonstrate the precision with which these durable residues can indicate the animal and plant materials worked with prehistoric stone tools.