Transferability of use-wear identification criteria between raw materials: insights from a blind test

Lithic use-wear analysis was originally dominantly developed for determining the uses of flint tools, and a large majority of archaeological applications continue to be focused on flint and flint-like rocks. While several relevant contributions have been made to extend the methodology to raw materials such as quartz and quartzite (e.g. Knutsson 1988; Pedergnana et al. 2017) and wear formation on igneous rocks is also under further investigation (e.g. Asryan et al. 2014), many non-flint rocks remain underexplored in terms of their potential for functional analysis. Equally lacking is a clear consensus as to what (if any) extent the principles of wear formation can be transferred from one raw material to the next. We address this question by discussing the results of a recent blind test and complementary analysis of experimentally used tools made of dolerite, hornfels, mudstone, quartz, and quartzite. The test was taken by an analyst who had previous experience in the analysis of flint, quartz, and, to a more limited extent, quartzite, but no prior experience with dolerite, hornfels, or mudstone. The artefacts were first analysed for use-wear under low magnification with a stereomicroscope (magnifications 6.5‒50×) and subsequently with the combined use of both low and high magnification (the latter achieved with a metallurgical microscope, magnifications 100‒500×). The interpretations from the two steps of analysis were handed in separately to allow examining the effect of analytical technique. The blind test results permit directly discussing the transferability of identification criteria and the potential risks involved, and shed light on the basic differences in macroscopic edge damage and microwear formation between the selected raw materials. With this contribution, we hope to encourage further discussion among experts to determine how to best construct lithic reference libraries and how to deal with the particularities of different raw materials in order to maximise their potential for functional studies.