FROM ARCHAEOLOGICAL DRAWING TO X-RAYS MICROTOMOGRAPHY ANALYSIS FOR TECHNO-FUNCTIONAL ANALYSIS: THE CASE OF STONE ARROWHEADS OF COPPA NEVIGATA (BRONZE AGE, SOUTHERN ITALY)

The modes of the archaeological documentation of prehistoric lithic tools has been widely debated among scholars for long time. In the recent years the introduction of new documentation techniques (e.g. 3D model and 3D scanner), besides the classic drawing, has increased the academic debating. Among these new documentation techniques, 3D photography is now commonly used while X-rays microtomography (μCT) has never be applied on chert artefacts. In the present work, graphite drawing, 3D photography and μCT are used for the techno-functional analysis. For this reason, four chert arrowhead (CN13, CN21, CN39, CN51) from the settlement of Coppa Nevigata (Bronze Age Southern Italy) were analysed with all these three techniques to retrace their different techno-functional sequences. Results show that μCT allows to detect more detachment areas and blows than graphite drawing and 3D photography. Moreover, internal defects and inclusions can be detected only by the use of μCT. In particular, CN39 shows an extensive internal cracking which can be imputed to a heating treatment. Furthermore, one surface of CN39 do not show any crack, which testify the removal of this portion in order to reuse the arrowhead after the heating event. In this way, μCT allowed to identify both a heating event and also its timing, since it occurred between the production and the retouch before a new use. In the case of CN51, the supposed heating identified after optical analysis seems not confirmed by μCT analysis. After the different analytical approaches, also the sample CN13 and CN21 do not show clear evidences of retouching and/or heating as archeologically supposed after optical analysis. Neither the stereoscope nor the 3D photography model give back the same informations obtained by μCT and highlight the potentials and limits of each one to detect microstructural details that can help to understand the techno-functional dynamics. The pros and cons of the old and the new documentation techniques were also discussed, in order to propose specific terms for microstructure description and interpretation