USEWEAR CHARACTERIZATION OF PREHISTORIC FLINTS WITH IBA

Archaeology has great interest in understanding the use of prehistoric stone tools. The observation of usewear on flint artefacts may allow one to determine the matter which was worked with them: clues for this identification are given by optical microscopy on "experimental" tools. Blind tests on modern replicas used to work known materials, such as bones, meat, plants, wood, etc., have had significant success. This classic method is still widely used by specialised archaeologists in the study of usewear. We have observed, with SEM coupled with a Si(Li) detector, that the composition of usewear is related to the composition of the worked material. Simultaneously, we have initiated a systematic study of different kinds of polishes (meat, bone, plants, wood) with the techniques of RBS, NRA and PIXE. This approach provides a new model of polish formation: the mineral components of the worked matter smoothen the roughness of the flint tools. Archaeological conclusions on Predynastic Egyptian flint knives (around 4000 B.C.) and Magdalenian burins from Etiolles, near Paris, France, (10 000 B.C.) are presented.