Why is it so difficult to work on geochemical composition? Supervised geochemical composition data processing to study colouring iron oxide-rich rocks in archaeological contexts

Abstract

Iron oxide-rich colouring materials exhibit substantial diversity across various contexts, encompassing a wide range of physical, chemical, petrographic, and mechanical characteristics. The identification of these materials holds the key to understanding exploited mineral resources and the criteria of selections in Palaeolithic societies. Geochemical methods delve into the intrinsic properties of rocks, offering insights into their historical records, including their formation, weathering transformation, and technical applications.

To support the comprehensive collection and analysis of geochemical data pertaining to such archaeological materials, this paper establishes a foundation based on a diverse iron oxide-rich reference rocks. The objective of this study is to ensure a consistent basis for comparison by 1) formulating measurement procedures tailored to the unique physical attributes of iron oxide-rich materials, 2) elucidating the geological formation and context in relation to material composition, and 3) facilitating comparisons between geochemical analyses conducted on archaeological specimens and compatible geological references, whether local, regional, or extra-regional.

This paper presents a comprehensive investigation of the geochemical composition of seven selected iron oxide-rich reference rocks. By integrating petrographic and mineralogical insights with a careful consideration of analytical and statistical constraints, it contributes a coherent and critically assessed framework for conducting geochemical analyses and statistical data processing on archaeological specimens and relevant reference rocks, leveraging non-invasive Proton-Induced X-ray Emission Spectroscopy (PIXE) data.