Ferruginous Raw Material Sources for Palaeolithic in Poland – Promising Results of Provenance Studies

Haematite and haematite bearing rocks is a common raw material in Palaeolithic. Widespread in nature, it occurrs either in isolated oucrops or in privileged litostratigraphic formations (in Central Europe these are Lower Devonian, Lower Permian, Lower Triassic and Upper Triassic rocks). All must have provoked an interest of Palaeolithic people so we have searched for a fingerprint for all. So far provenance studies of ferruginous rocks used to be based on their chemical composition, mineral composition and magnetic properties. We have applied all but another one seems to be promising: haematite crystallite size measured both in natural samples and artefacts. Samples from Poland and other Central Europe countries (Czech, Slovakia, Croatia) have been analysed; they represent various litostratigraphic formations (incl. mentioned above), genetic types and geochronology. Artefacts represent, among others, Aurignacian site (Klissoura, Greece) and Magdalenian site (Dzierżysław, Poland; Hostim, Czech). Systematic measurements of haematite crystallite size point at differences of this parameter depending on the origin and age of a rock (e.g. Lower Triassic haematite rock of residual origin, with its, averagely, 500 angstrem; Precambrian haematite of metamorphic origin with 3000 angstrem and haematite from contemporary terra rosa with ca. 80 angstrem). Large assemblage of examined samples enables us to: a) discuss pros and cons of application of this approach, b) determine, to some degree, a sourcing area for artefacts, c) determine a homogeneity of an assemblage, d) discern intentional powdery remnants from their natural counterparts. INTRODUCTION Provenance studies of ferruginous materials and artefacts made of them (haematite, haematite-bearing rocks and ochre) have long been recognised as complex due to the wide abundance of the iron minerals and rocks in the natural environment, the complexity of genetic processes standing behind them and the diversity of their mineralogical and chemical features [13]. Macrofeatures of artefacts can be described easily and then compared with a source material from a data base but a provenance study of the powdered rock or a mineral seems to be impossible. Another problem with the fine grained material concerns the difference between a natural ferruginous powder (e.g. a hardpan, soil iron oxides or Terra Rosa) and a powder introduced originally into an archaeological layer or onto a surface of an artefact. However, it seems that a solution exists: a fingerprint can be searched for in haematite microstructure. Haematite (a mineral itself and a compound in natural mixtures, like haematite-bearing rocks and ochres) has numerous varieties differing in colour and hardness. It results from its micromorphological properties, among them crystallite size. The latter is a consequence of variety of both: natural and human provoked processes, that have been long researched [3]. A crystallite itself can be defined as a microarea that coherently disperses X ray radiation. Crystallite size measurement may contribute to haematite powder artefacts provenance studies (Fig. 1). 1 9th International Conference on NDT of Art, Jerusalem Israel, 25-30 May 2008 For more papers of this publication click: www.ndt.net/search/docs.php3?MainSource=65