Exploring Basalt: A Methodological Framework for Analysing Wear Traces on Basalt Tools

Journal of Archaeological Method and Theory https://doi.org/10.1007/s10816-024-09663-8 RESEARCH Exploring Basalt: A Methodological Framework for Analysing Wear Traces on Basalt Tools Lena Asryan1 · Veerle Rots1,2 Accepted: 11 July 2024 © The Author(s) 2024 Abstract Basalt is a widely used raw material for tool manufacture at prehistoric sites, but a unified methodology for assessing how hominfins used basalt in prehistory is lacking. A comprehensive experimental investigation of basalt tools is, thus, necessary to establish a reliable methodological framework that can be used to explore the functional properties of archaeological basalt assemblages. The aim of this study is to contribute to the development of a methodological framework for the analysis of use-wear on basalt tools. Basalt, characterised by its distinct mechanical and structural properties and unique response to mechanical stress, requires specialised treatment and investigation. To address this, our basalt varieties were characterised using SEM–EDS analysis. Sequential experiments were conducted, using the experimental basalt tools in different activities, including butchery, hide, bone and woodworking to determine usewear formation patterns. Subsequentially, various analytical tools, including optical and scanning electron microscopes, were used to analyse macro- and micro-wear traces on basalt. Our results provide useful information on methodological aspects of use-wear formation on basalt. The inclusion of detailed cleaning and experimental protocols enhanced the robustness of our methodology. Furthermore, the combined utilisation of various microscopes enabled to compile a comprehensive and complementary information on such a complex raw material such as basalt and to characterise thoroughly the diagnostic features of the micro-wear traces (e.g. edge damage, rounding, polish). Keywords Basalt · Micro-wear analysis · Methodological approach · Experiments · Multi-technique analysis * Lena Asryan 1 TraceoLab, University of Liège, Place du 20‑Août 7, 4000 Liège, Belgium 2 F.R.S.-FNRS, Brussels, Belgium 13 Vol.:(0123456789) L. Asryan, V. Rots Introduction The field of micro-wear analysis on prehistoric lithic artefacts has experienced a substantial transformation over the past six decades. This evolution can be attributed not only to advancements in modern technology and the development of more sophisticated analytical techniques but also to notable progress in methodological approaches. Traditionally, the majority of micro-wear studies were focused on chert or flint (e.g. Tringham et al., 1974; Odell, 1977; Keeley, 1980; Vaughan, 1985; Grace, 1989; González and Ibañez, 1994; Levi-Sala, 1996), leading to the most extensive development of micro-wear methodology for this raw material. The “preference” for flint can be attributed to several factors, with the abundance of this raw material in numerous archaeological sites and the conspicuous ease of observing wear patterns using optical light microscopes on flint or chert materials standing out as primary reasons. This does not imply a lack of effort or investigations into nonflint raw materials. In fact, numerous researchers (e.g. Kamminga, 1978; Greiser & Sheets, 1979; Foix & Bradley, 1985; Knutsson, 1988; Knutsson et al., 1988; Richards, 1988; Sussman, 1988; Hurcombe, 1992; Pereira, 1996) made significant contributions by establishing essential methodological frameworks for the examination of micro-wear on non-flint raw materials. However, most of these researchers recognised the difficulties of analysing “coarser” raw materials given the analytical challenges imposed by the physical and mechanical properties of these raw materials. Along with the progress of new analytical tools and equipment and driven by the pervasive occurrence of non-flint raw materials at numerous prehistoric sites, there has been a growing interest in recent years in developing further the microwear studies on non-flint raw materials such as quartz, quartzite, rock crystal, and various types of lava (Aleo, 2023; Bello-Alonso et al., 2019, 2020; Clemente Conte et al., 2015; Fernández-Marchena & Ollé, 2016; Lemorini et al., 2014; Ollé et al., 2016; Pedergnana & Ollé, 2017; Pedergnana et al., 2016a, 2020; Taipale & Rots, 2019). Notably, the adoption of novel analytical techniques and methods (e.g. differential interference contrast (DIC) in optical microscopes, scanning electron microscopy (SEM), 3D digital and confocal microscopes), as proposed in some of these studies, has substantially enhanced the ability to overcome the analytical limitations imposed by the unique physical properties of these rocks. Different lavas in general, and basalt in particular, have attracted the attention of researchers in the field of micro-wear studies almost since the beginning of the discipline (Price-Beggerly,1976; Wyant and Bayham, 1976; Stafford, 1977; Kamminga, 1978; Montgomery, 1978; Odell, 1980; Foix and Bradley, 1985; Richards, 1988). These early works established a comprehensive methodological framework for micro-wear analysis on basalt, accompanied by a diverse experimental programme covering a wide range of activities and some basalt varieties. Subsequently, researchers have continued to contribute to the field by developing experimental programmes involving different types of lava, such as andesite, dolerite, basalt, rhyolite, and obsidian (Hurcombe, 1992; McDevitt, 1994; 13 Exploring Basalt: A Methodological Framework for Analysing… Rodríguez Rodríguez, 1997, 2009; Clemente Conte and Gibaja, 2009; Asryan et al., 2014; Clemente Conte et al., 2015; Bello-Alonso et al., 2019, 2020; Aleo, 2023). Nevertheless, despite the considerable interest and research dedicated to advancing micro-wear studies on basalt and other types of lava, there are several crucial aspects that remain unexplored or insufficiently investigated. (1) One of these aspects, as underscored also by Richards (1988) and still relevant today, is the significant variability within basalt. This variability encompasses divers mineral sizes (coarse to fine), nature (tough to more fragile), and textures (rough to glassy) influencing on the type of wear patterns that develop on tools made of different basalts. Such a variable nature of basalt demands careful consideration and control of numerous factors within the raw material itself during experimentation. Consequently, making close comparisons between various experimental basalt tools utilised in identical activities and under the same conditions frequently proves to be a challenging task. (2) The experimental reference collections for basalt lag behind those of more common materials like flint or obsidian. To address this, it is crucial to construct an experimental reference collection that will serve, firstly, to gain insights into the behaviour of basalt under varied experimental conditions and wear development when working with diverse materials; secondly, to (...truncated)