The Application of the Multi-Layered Chert Sourcing Approach (MLA) for the Characterisation and Differentiation of ‘Chocolate Silicites’ from the Holy Cross Mountains, South-Central Poland

Abstract

Chocolate silicites from the Świetokrzyskie (Holy Cross) Mountains in south-central Poland were widely used for stone tool production from Middle Palaeolithic times to the Early Iron Age. Their presence extends beyond Poland into lithic assemblages from the Czech Republic, Slovakia, Hungary and eastern Austria. Outcrops of this material are situated within a narrow strip of Mesozoic (Upper Jurassic) sediments at the northeastern footslopes of the Holy Cross Mountains. Attempts of a raw material characterisation were repeatedly undertaken, however, a clear differentiation of the visually defined subvarieties was never achieved. For the present study, we applied the Multi-Layered Chert Sourcing Approach (MLA) by combining macroscopic, microscopic and geochemical analyses using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) to samples from five chocolate silicite deposits in order to characterise the materials and to assess the potential of a source differentiation. Secondly, we included chert samples from Sąspow near Krakow for differentiation on a larger scale. Our results illustrate that a source separation of Holy Cross Mountains chocolate silicites is possible to a certain extent – there are limitations due to their geographic proximity and the resulting similar geologic genesis environments. However, our study showed clear possibilities to differentiate chocolate silicites from Jurassic-Krakow silicites based on characteristic microfossil inclusions and trace element contents.