Thermal Alteration of Flint: An Experimental Approach to Investigate the Effect on Material Properties

Archaeological lithic assemblages are often affected by burning, as evident from severe thermal damage on these artefacts. In this study, the thermal alteration of four different flint types was investigated by performing controlled heating experiments in laboratory setting. The resulting heat alterations were afterwards compared to heating of flint samples in campfire experiments, as these correspond better to the burning conditions present during prehistoric times. The microstructural and chemical changes occurring in flint during heating were analyzed using different macroscopic (visual observations and color measurements) and microscopic (optical microscopy and non-destructive X-ray micro-CT) techniques. Eventually, the terminology regarding the degree of heat exposure was refined and complemented with temperature ranges and color information for the investigated flint types. In doing so, this study provides criteria for a more objective macroscopic determination of the burning degree of archaeological flint artefacts, that could be useful in a wide range of lithic studies.