Siliceous rocks from the southern part of the Kraków-Częstochowa Upland (Southern Poland) as potential raw materials in the manufacture of stone tools – A characterization and possibilities of identification

•Differential types of siliceous rocks as raw materials for production of stone tools in S Poland.•Identification of chert concretions, bedded cherts and epigenetic siliceous rocks.•Credibility of provenance determination of siliceous raw materials upon macroscopic features.•Microfacies and X-ray diffraction analyses as basic methods for determinations of siliceous rocks. The Upper Jurassic sediments from the Kraków-Częstochowa Upland developed as carbonates, mostly limestones, which represent the microbial-sponge megafacies that were typical of the northern margin of the Tethys Ocean. Outcrops of these rocks are scattered along an extended belt ranging from Portugal to the Caucasus Mts. One of the common features of the bedded limestones belonging to this megafacies is the local occurrence of chert concretions. The siliceous rocks embedded within the Upper Jurassic sequences from the southern part of the Kraków-Częstochowa Upland originated from a broad spectrum of limestone silicification processes and are represented by chert concretions, bedded cherts and epigenetic siliceous rocks. These rocks served as raw materials in the production of stone tools from the Middle Palaeolithic onwards. These tools have been studied extensively by archaeologists. This paper presents the identification of the above mentioned types of siliceous rocks used in the manufacture of tools based upon (i) microscopic observations of thin sections which reveal the primary microfacies of limestones subjected to silicification, and (ii) X-ray diffraction analyses, including the determination of the crystallinity index of SiO2. Unfortunately, the available research methods do not permit the identification of the varieties of chert concretions to an extent that would permit them to be even roughly connected with particular outcrops or, at least, with particular regions of the occurrence of siliceous raw materials on a Pan-European scale. Macroscopic criteria have recently been adopted in archaeological classifications aimed at determining the origin of stone tools and drawing conclusions as to the source outcrops or regions. However, regrettably, these have proven groundless from the geological point of view.