Aspects and characterization of chert alteration in an archaeological context: A qualitative to quantitative pilot study

Abstract

Chert alteration in Paleolithic contexts, generally known as "patina" by prehistorians, has long been recognized. Originally, different types of "patina" were defined as "white patina", "glossy patina", or "porcelain-like patina", all of which involved changes in the color and/or roughness of the initial raw material. Alteration degrees are used in many research fields like taphonomy, petroarchaeology or usewear analysis; however most of these studies are still based on qualitative descriptions using a wide range of terms that bring about confusion. In this paper, we present first the results of an inter-observer's blind-test where color and roughness are described at macroscopic scale. Secondly, we use quantitative methods to compare archaeological and experimental altered silicifications: light spectrometry and confocal microscopy are used to quantify color and roughness. We show here how macroscopic qualitative descriptions could lead to confusion because of the lack of calibration and the number of terms used differently by each one. We demonstrated the efficiency of quantitative methods as light spectrometry and confocal microscopy that will significantly enhance studies of surface alteration in terms of taphonomy, use-wear analyses, and petroarchaeology issues as well as interdisciplinary discussions.

Bidirectional blade technology on naviform cores from northern Arabia: New evidence of Arabian‐Levantine interactions in the Neolithic

“…Artifacts displaying severe edge damage due to displacement are rare and arrises are sharp, with some exceptions caused by modern disturbance (oil survey tracks crisscross the entire landscape and caused considerable damage). Some specimens present patches of white alteration, possibly representing an initial desilicification of surface (Caux et al, ).…”

Evaluating the microscopic effect of brushing stone tools as a cleaning procedure

“…Although in the domain of traceology confocal microscopy has mainly been used to quantify userelated polish (e.g., Stemp et al, 2013;Ibáñez et al, 2014;2018;Macdonald et al, 2018), it can also be used to quantify changes in surface textures due to other causes (e.g. post-depositional alterations Vietti, 2016;Caux et al, 2018;Werner, 2018;Galland et al, 2019). There are multiple causes for the formation of wear.…”

The Late Gravettian Site of Kostënki 21 Layer III, Russia: a Chronocultural Reassessment Based on a New Interpretation of the Significance of Intra-site Spatial Patterning

“…There are a number of factors that contribute to the patination of flint artefacts, and although one of these factors is the amount of time elapsed since the flint was knapped, it is not necessarily the case that more heavily patinated artefacts are older than less heavily patinated artefacts. Other contributory factors include the chemical properties of the flint itself (which varies between different sources) and the depositional environment in which the artefact has been preserved (Hurst and Kelly 1961;Kovnurko 1971;Rottländer 1975;Glauberman and Thorson 2012;Thiry et al 2014;Caux et al 2018). In the case of Kostënki 21/III, there are three possible explanations, which are not mutually exclusive, for the patterning that we see:…”