Raw material quality is commonly related to the mineralogical structure (e.g., grain size and shape) and purity of a given material. Sedimentary rocks such as chert, flint, silicified shale, and other silica rich rocks were commonly used, and this is presumed to be due to their predictable fracturing properties and good knapping qualities. Such studies can help to understand the way in which people took advantage of the mechanical attributes of rocks that affect reduction sequences and edge-wear properties of tools. People selected different types of rocks to influence the technology and type of tools manufactured. In recent years, the study of lithic raw materials used by prehistoric hunter-gatherers for the production of stone tools has received much attention. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist. We acknowledge support by the Open Access Publishing Fund of the University of Tübingen. Map data sources: Global Administrative areas (GADM), vector and raster map data from Natural Earth ( and Shuttle Radar Topography Mission (SRTM) Version 4 ( ).įunding: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement n☇14842 PALAEOSILKROAD project). The work is made available under the Creative Commons CC0 public domain dedication.ĭata Availability: All relevant data are within the manuscript. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. Received: OctoAccepted: MaPublished: April 22, 2022 PLoS ONE 17(4):Įditor: Enza Elena Spinapolice, Sapienza University of Rome: Universita degli Studi di Roma La Sapienza, ITALY This work also offers first insight into the quality of archaeological porphyry that was utilised as a primary raw material at various Upper Palaeolithic sites in the Inner Asian Mountain Corridor from 47–21 ka cal BP.Ĭitation: Namen A, Iovita R, Nickel KG, Varis A, Taimagambetov Z, Schmidt P (2022) Mechanical properties of lithic raw materials from Kazakhstan: Comparing chert, shale, and porphyry. However, our analysis suggests that different raw materials are not different in terms of indentation fracture resistance. Previously, porphyry was thought to be of lower quality due to the anisotropic composition and coarse feldspar and quartz phenocrysts embedded in a silica rich matrix. The results show that materials, such as porphyry possess fracture toughness values that can be compared to those of chert. These tests were complemented by traditional petrographic studies to characterise the mineralogical composition and evaluate the level of impurities that could have potentially affected the mechanical properties. Selected samples of aforementioned rocks were tested by means of Vickers and Knoop indentation methods to determine the main aspect of their mechanical properties: their indentation fracture resistance (a value closely related to fracture toughness). In this work, we investigate geological and archaeological lithic raw material samples of chert, porphyry, and shale collected from the Inner Asian Mountain Corridor (henceforth IAMC). However, such comprehensive investigations are lacking for the Palaeolithic of Kazakhstan. In order to make objective assessments of raw material quality, we need to measure their mechanical properties (e.g., fracture resistance, hardness, modulus of elasticity). The study of lithic raw material quality has become one of the major interpretive tools to investigate the raw material selection behaviour and its influence to the knapping technology.
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