Flint tempering
Tempering of flint describes the thermal treatment ( tempering ) of flint , especially chert .
In prehistory and early history , the term tempering is used for the targeted heating of flint raw materials in order to improve the processing properties or the color of the rock. It causes a change in the rock structure and can be recognized by its color and surface texture. The fissile nature of the mineral is considerably increased in that with the same amount of force after thermal treatment, the kinetic energy ( kinetic energy ) travels longer distances in the rock than in the untreated rock, so that larger fissure surfaces are created. Alternatively, one could formulate that tempering allows a significantly reduced expenditure of force and still sufficiently large gap surfaces can be created.
Is chert like flint z. B. under a sand cover, heated for some time to temperatures around 350 ° C, a structural change occurs. Through the experimental archeology the possibility of such a structural change was for artifacts shown. Fire hardening has dominated Homo sapiens for 72,000 years in stone tools made of chert, it has been occurring for 164,000 years (location Pinnacle Point in South Africa).
A particularly characteristic feature of tempering is a semi-gloss sheen, which, however, is only present on make-up negatives that have been applied after the heat treatment. The color variations from red, pink to gray depend on the mineral composition. The higher the iron content in the stone, the greater the reddening. If the stone contains more manganese , its color plays into the gray.
Flint that has been fired white and structurally broken by heat is called calcined flint by archaeologists .
Even wood can be cured by heating, but not all types of wood lend themselves equally. A spruce stick in the vicinity of the Schöningen spears , known as a “spit” , may have been deliberately hardened in the fire, while fire hardening is doubted for the roughly equally old lance tip from Clacton-on-Sea and the Eemzeit lance from Lehringen .
Tempering of metals for the thermal change of material properties is also known from findings from the later metal ages .
literature
- Berit Valentin Eriksen: Implications of thermal pretreatment of chert in the German Mesolithic. In: R. Schild & Z. Sulgostowska (Eds.): Man and Flint. Proceedings of the VIIth International Flint Symposium. Warsaw, 1997, pp. 325-329
- Friedrich Gumbsch: Traces of the Middle Stone Age in Böblingen. In: Günter Scholz (Ed.): Traces of the Stone Age in Böblingen. Böblingen 1990, p. 31 (Böblinger Museumsschriften 2, online ).
- Jürgen Weiner: The improvement of the processing properties of amorphous rock types through controlled thermal treatment. A reading list. In: Communications Archaeologia Venatoria. 9, 1985, pp. 39-47.
Individual evidence
- ^ Berit V. Eriksen: Colorful Lithics - the “Chaîne Opératoire” of Heat Treated Chert Artefacts in the Early Mesolithic of Southwest Germany. In: CJ Kind (ed), After the Ice Age. Settlements, subsistence and social development in the Mesolithic of Central Europe. Konrad Theiss publishing house. Stuttgart, 2006, 147-153
- ↑ Kyle S. Brown, Curtis W. Marean, Andy IR Herries, Zenobia Jacobs, Chantal Tribolo, David Braun, David L. Roberts, Michael C. Meyer, Jocelyn Bernatchez: Fire as an engineering tool of early modern humans. In: Science . Volume 325, No. 5942, August 14, 2009, pp. 859-862.
- ↑ Hartmut Thieme: Charred wooden stick. Old Paleolithic wooden tools from Schöningen, district of Helmstedt. Significant finds on the cultural development of early humans. In: Germania . Volume 77, No. 2, 1999, pp. 474-478
- ^ AJ Cosner: Fire hardening of wood. In: American Antiquity. 22, 1956, pp. 179-180
- ^ Jürgen Weiner: Knowledge - Tool - Raw Material. A vademecum on the technology of stone age woodworking. In: Archaeological Information. Volume 26, No. 2, 2003, pp. 407-426 doi: 10.11588 / ai.2003.2.12704