Influence of intrinsic properties of prehistoric stone tool materials on development of use-wear traces

Abstract

Detailed analysis of use-wear traces remaining on archaeological stone implements is one of the most important procedures to reveal the functions of prehistoric tools. In this study, the influence of the material properties of tools on generation and growth of such use-wear traces was investigated by an abrasion test on four di erent types of rocks that were used in prehistoric ages in Japan : obsidian, shale, chert, and andesite (sanukite). Consequently, wear tendency noticeably varied for each rock type. Specifically, andesite (sanukite) exhibited a high rate of wear progress with large variation whereas that of chert was low and uniform. Moreover, on the basis of the relationship between rock hardness and wear depth, the samples can be divided into two groups : microcrystalline rocks, including shale and chert, where an inverse relationship between hardness and wear depth was observed, and obsidian and andesite (sanukite), where no definite correlation was found between these factors. According to electron microscopic observations, grain removal was predominantly exhibited in the wear process of shale and chert, whereas much smoother surfaces, with few or no imprints of particle removal, were captured in the wear surfaces of andesite (sanukite) and obsidian. Additionally, the result of a cutting test using two types of shale was consistent with the consequences of the abrasion test. In particular, microcrystalline rocks with di erent levels of hardness could su er di erent rates of wear on the basis of their susceptibility to wear. The results obtained in this study imply that it is highly possible that intrinsic material properties of rocks greatly governed the usewear development on prehistoric tools. Thus, detailed analyses of materials can provide helpful information for the accurate interpretation of the use-wear traces generated on archaeological implements.Received January , . Accepted May , . * Tokyo , Japan. * Department of Mechanical Engineering, Keio University. Hiyoshi, Kohoku-ku, Yokohama, , Japan. * a Corresponding author : Yonekura@hyper.rcast.u-tokyo. ac. jp of human history. According to previous works, nificantly a ected by a variety of factors. For instance, Odell ( ) listed several variables Detailed analyses of use-wear traces remainthat should be considered important parameing on archaeological stone tools are proceters influencing wear results in experiments : dures fundamental to revealing the functions types of stone used for the tools, fracture propand roles of the implements in the early stages erties of the rock materials, types of stroke used in performance of an activity, stroke such use-wear formation could have been siglengths, frequencies of strokes per unit time,

The effect of worked material hardness on stone tool wear

“…Until now, systematic mechanical tests of archaeologically-relevant target materials have not been incorporated into lithic use-wear research. In particular, hardness tests were carried out on the stones themselves [26][27][28][29], but not on the target materials. For this reason, we decided to carry out a test of the target material hardnesses and to evaluate their role in abrading flint.…”

The effect of worked material hardness on stone tool wear

“…Until now, systematic mechanical tests of archaeologically-relevant target materials have not been incorporated into lithic use-wear research. In particular, hardness tests were carried out on the stones themselves [34][35][36][37], but not on the target materials. For this reason, we decided to carry out a test of the target materials' hardnesses and to evaluate their role in abrading flint with the expectation that the harder the worked material is the more surface modifications will develop on flint.…”