Microhardness analysis and characterization of Palaeolithic stone tool materials for understanding primary material selections and utilizations

For a comprehensive understanding of material selection and utilization at the beginning of human history, the mechanical properties, surface morphologies, surface roughness, and internal microstructures of lithic raw materials used in the Upper Paleolithic age are analyzed. A case study reveals that certain materials with hardness greater than approximately 6.0 GPa with even surfaces, which were composed of extremely fine crystal grains with diameters from approximately 0.1 to 0.5 µm, were elaborately selected for fabricating sharp-edged blades. Additionally, material influence on the progress of the manufacture of tools was observed: materials with high hardness and strength tended to halt the manufacture process in the initial stages, whereas materials with low hardness and strength tended to facilitate the fabrication process to the final stages. These results demonstrate that detailed analyses of the intrinsic properties of actual prehistoric materials could provide useful and significant information for understanding material-related activities in prehistoric ages.