Thermal transformation of chalcedonite artefacts from the Magdalenian site of Ćmielów 95”Mały Gawroniec” (Poland)

Abstract

Two chalcedonite artefacts from the Magdalenian site of Cmiel ow 95 (Poland), with macroscopic features suggestive of thermal treatment, were subjected to a multi-instrumental analysis. The red upper layer of the objects consists of "protohematite", implying temperature-driven, goethite-to-hematite transition. The red layer shows traces of carbonized matter with saccharides and levoglucosan (from burning wood) as well as fatty acids. PXRD data suggest a source of higher temperatures (up to $800 C) within the bottom layer, with $200-300 C range ascribed to the red layer. On the basis of the collected data the artefacts are proposed to be relics of cooking stones.