Advertisement

Physics and Chemistry of Minerals

, Volume 44, Issue 1, pp 21–31 | Cite as

Detailed near-infrared study of the ‘water’-related transformations in silcrete upon heat treatment

  • Patrick SchmidtEmail author
  • Christoph Lauer
  • Gerald Buck
  • Christopher E. Miller
  • Klaus G. Nickel
Original Paper

Abstract

In archaeology, lithic heat treatment is the process of modifying a rock for stone tool production using fire. Although the earliest known cases of heat treatment come from South Africa and involved silcrete, a microcrystalline pedogenic silica rock, its thermal transformations remain poorly understood. We investigate the ‘water’-related transformations in silcrete using direct transmission near-infrared spectroscopy. We found that SiOH is noticeably lost between 250 and 450 °C and hydroxyl reacts with H2O, part of which is trapped in the structure of the rocks. This water can only be evaporated through heat-induced fracturing at high temperatures, imposing maximum temperatures for silcrete heat treatment of approximately 500 °C. Between 250 and 450 °C new siloxane bonds are formed according to the reaction 2SiOH → Si–O–Si + H2O, which can be expected to transform the rock’s mechanical properties. The tolerance of silcrete for relatively fast ramp rates can be explained by its pore volume and low SiOH content, ensuring good water evaporation. These results shed light on the processes taking place in silcrete during heat treatment and allow for a better understanding of the parameters needed for it.

Keywords

Lithic heat treatment Thermal transformations Silica rocks Near FTIR South African silcrete MSA heat treatment 

Notes

Acknowledgments

We thank the Deutsche Forschungsgemeinschaft (DFG) for funding of the research project Heat Treatment in the South African MSA that made the present study possible (Grant No: CO 226/25-1, MI 1748/2-1, NI 299/25-1) and for funding the Agilent Cary 660 spectrometer used for parts of this study (MI 1748/1-1). We also thank Junichi Fukuda and an anonymous reviewer for their corrections and suggestions during the review process for this publication.

Supplementary material

269_2016_833_MOESM1_ESM.pdf (527 kb)
Supplementary material 1 (PDF 527 kb)

References

  1. Aines RD, Rossman GR (1984) Water in minerals? A peak in the infrared. J Geophys Res 89:4059–4071. doi: 10.1029/JB089iB06p04059 CrossRefGoogle Scholar
  2. Anderson jr JH (1965) Calorimetric vs. infrared measures of adsorption bond strengths on silica. Surf Sci 3:290–291CrossRefGoogle Scholar
  3. Anderson jr JH, Wickersheim KA (1964) Near infrared characterization of water and hydroxyl groups on silica surfaces. Surf Sci 2:252–260CrossRefGoogle Scholar
  4. Benesi HA, Jones AC (1959) An infrared study of the water–silica gel system. J Phys Chem 63:179–182. doi: 10.1021/j150572a012 CrossRefGoogle Scholar
  5. Binder D (1984) Systèmes de débitage laminaire par pression: exemples chasséens provençaux. In: Tixier J, Inizan ML, Roche H (eds) Préhistoire de la pierre taillée, 2: économie du débitage laminaire: technologie et expérimentation: IIIe table ronde de technologie lithique. Meudin-Bellevue, october 1982. Cercle de Recherches et d’Etudes Préhistoriques, Paris, pp 71–84Google Scholar
  6. Bordes F (1969) Traitement thermique du silex au Solutréen. Bull Soc Préhist Fr 66:197CrossRefGoogle Scholar
  7. Brown KS et al (2009) Fire as an engineering tool of early modern humans. Science 325:859–862CrossRefGoogle Scholar
  8. Cochrane GWG, Habgood PJ, Doelman T, Herries AIR, Webb JA (2012) A progress report on research into stone artefacts of the southern Arcadia Valley, central Queensland. Aust Archaeol 75:104–109CrossRefGoogle Scholar
  9. Corkill T (1997) Red, yellow and black: colour and heat in archaeological stone. Aust Archaeology 45:54–55CrossRefGoogle Scholar
  10. Crabtree DE, Butler BR (1964) Notes on experiment in flint knapping: 1 heat treatment of silica materials. Tebiwa 7:1–6Google Scholar
  11. Eriksen BV (2006) Colourful lithics—the “Chaîne Opératoire” of Heat Treated Chert Artefacts in the Early Mesolithic of Southwest Germany. In: Kind CJ (ed) After the ice age. Settlements, subsistence and social development in the Mesolithic of Central Europe, Materialhefte zur Archäologie in Baden-Württemberg. Stuttgart: Konrad Theiss Verlag, pp 147–153Google Scholar
  12. Flörke OW, Köhler-Herbertz B, Langer K, Tönges I (1982) Water in microcrystalline quartz of volcanic origin: agates. Contrib Miner Petrol 80:324–333CrossRefGoogle Scholar
  13. Flörke OW, Graetsch H, Martin B, Roller K, Wirth R (1991) Nomenclature of micro- and non-crystalline silica minerals, based on structure and microstructure. Neues Jahrb Miner Abh 163:19–42Google Scholar
  14. Frondel C (1982) Structural hydroxyl in chalcedony (type B quartz). Am Mineral 67:1248–1257Google Scholar
  15. Fukuda J, Peach CJ, Spiers CJ, Nakashima S (2009) Electrical impedance measurement of hydrous microcrystalline quartz. J Mineral Petrol Sci 104:176–181. doi: 10.2465/jmps.081022f CrossRefGoogle Scholar
  16. Graetsch H, Flörke OW, Miehe G (1985) The nature of water in chalcedony and opal-C from brazilian agate geodes. Phys Chem Miner 12:300–306CrossRefGoogle Scholar
  17. Grim R (1962) Applied clay mineralogy. International series in the earth sciences. McGraw-Hill, New YorkGoogle Scholar
  18. Hanckel M (1985) Hot rocks: heat treatment at Burrill Lake and Currarong, New South Wales. Archaeol Ocean 20:98–103CrossRefGoogle Scholar
  19. Hiscock P (1993) Bondian technology in the Hunter Valley, New South Wales. Archaeol Ocean 28:65–76CrossRefGoogle Scholar
  20. Kronenberg AK (1994) Hydrogen speciation and chemical weakening of quartz. In: Heaney PJ, Prewitt CT, Gibbs GV (eds) Silica: physical behaviour, geochemistry and materials applications. Reviews in Mineralogy 29. Mineralogical Society of America, Washington, pp 123–176Google Scholar
  21. Langer K, Flörke OW (1974) Near infrared absorption spectra (4000–9000 cm-1) of opals and the role of “water” in these SiO2 ·nH2O minerals. Fortschr Mineral 53:17–51Google Scholar
  22. Lauer C (2014) Tempern von Silcrete—Liegt der Verbesserung der Zuschlagbarkeit derselbe Mechanismus zugrunde wie bei Flint? Unpublished Bachelor thesis, Eberhard Karls University of TübingenGoogle Scholar
  23. Léa V (2005) Raw, pre-heated or ready to use: discovering specialist supply systems for flint industries in mid-Neolithic (Chassey culture) communities in southern France. Antiquity 79:1–15Google Scholar
  24. McDonald RS (1958) Surface functionality of amorphous silica by infrared spectroscopy. J Phys Chem 62:1168–1178. doi: 10.1021/j150568a004 CrossRefGoogle Scholar
  25. McLaren AC, Cook RF, Hyde ST, Tobin RC (1983) The mechanisms of the formation and growth of water bubbles and associated dislocation loops in synthetic quartz. Phys Chem Miner 9:79–94. doi: 10.1007/bf00308151 CrossRefGoogle Scholar
  26. Mercieca A, Hiscock P (2008) Experimental insights into alternative strategies of lithic heat treatment. J Archaeol Sci 35:2634–2639CrossRefGoogle Scholar
  27. Micheelsen H (1966) The structure of dark flint from Stevns, Denmark. Medd Dansk Geol Foren 16:285–368Google Scholar
  28. Mourre V, Villa P, Henshilwood CS (2010) Early use of pressure flaking on lithic artifacts at Blombos Cave, South Africa. Science 330:659–662CrossRefGoogle Scholar
  29. Porraz G, Texier P-J, Archer W, Piboule M, Rigaud J-P, Tribolo C (2013) Technological successions in the Middle Stone Age sequence of Diepkloof Rock Shelter, Western Cape, South Africa. J Archaeol Sci 40:3376–3400. doi: 10.1016/j.jas.2013.02.012 CrossRefGoogle Scholar
  30. Roberts DL (2003) Age, genesis and significance of south african coastal belt silcretes, Memoir 95. Council for Geoscience, PretoriaGoogle Scholar
  31. Roqué-Rosell J et al. (2010) Influence of heat treatment on the physical transformations of flint used by neolithic societies in the Western Mediterranean. In: International conference, materials research society, Boston, 2010. pp mrsf10-1319-ww1309-1302Google Scholar
  32. Rowney MAASC (1994) Palaeomagnetic tests of heat treated silcrete artefacts. Aust Aborig Stud 1:39–43Google Scholar
  33. Schmidt P (2011) Traitement thermique des silicifications sédimentaires, un nouveau modèle des transformations cristallographiques et structurales de la calcédoine induites par la chauffe. Unpublished doctoral thesis, Muséum national d’histoire naturelleGoogle Scholar
  34. Schmidt P (2014) What causes failure (overheating) during lithic heat treatment? Archaeol Anthropol Sci 6:107–112. doi: 10.1007/s12520-013-0162-3 CrossRefGoogle Scholar
  35. Schmidt P, Fröhlich F (2011) Temperature dependent crystallographic transformations in chalcedony, SiO2, assessed in mid infrared spectroscopy. Spectrochim Acta Part A Mol Biomol Spectrosc 78:1476–1481CrossRefGoogle Scholar
  36. Schmidt P, Mackay A (2016) Why was silcrete heat-treated in the middle stone age? An early transformative technology in the context of raw material use at Mertenhof Rock Shelter, South Africa. PLoS ONE 11:e0149243. doi: 10.1371/journal.pone.0149243 CrossRefGoogle Scholar
  37. Schmidt P, Badou A, Fröhlich F (2011) Detailed FT near-infrared study of the behaviour of water and hydroxyl in sedimentary length-fast chalcedony, SiO2, upon heat treatment. Spectrochim Acta Part A Mol Biomol Spectrosc 81:552–559CrossRefGoogle Scholar
  38. Schmidt P et al (2012) Crystallographic and structural transformations of sedimentary chalcedony in flint upon heat treatment. J Archaeol Sci 39:135–144CrossRefGoogle Scholar
  39. Schmidt P, Porraz G, Slodczyk A, Bellot-gurlet L, Archer W, Miller CE (2013a) Heat treatment in the South African Middle Stone Age: temperature induced transformations of silcrete and their technological implications. J Archaeol Sci. doi: 10.1016/j.jas.2012.10.016 Google Scholar
  40. Schmidt P, Slodczyk A, Léa V, Davidson A, Puaud S, Sciau P (2013b) A comparative study of the thermal behaviour of length-fast chalcedony, length-slow chalcedony (quartzine) and moganite. Phys Chem Miner 40:331–340. doi: 10.1007/s00269-013-0574-8 CrossRefGoogle Scholar
  41. Schmidt P et al (2015) A previously undescribed organic residue sheds light on heat treatment in the Middle Stone Age. J Hum Evol 85:22–34CrossRefGoogle Scholar
  42. Scholze H (1960) Über die quantitative UR-spektroskopische Wasserbestimmung in Silikaten. Fortschr Mineral 38:122–123Google Scholar
  43. Summerfield MA (1983) Petrography and diagenesis of silcrete from the Kalahari Basin and Cape coastal zone, Southern Africa. J Sediment Res 53:895–909Google Scholar
  44. Tiffagom M (1998) Témoignages d’un traitement thermique des feuilles de laurier dans le Solutréen supérieur de la grotte du Parpalló (Gandia, Espagne) Paléo 10:147–161Google Scholar
  45. Wilke PJ, Flenniken J, Ozbun TL (1991) Clovis Technology at the Anzick Site, Montana. J Calif Great Basin Anthropol 13:242–272Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Department of Prehistory and Quaternary EcologyEberhard Karls University of TübingenTübingenGermany
  2. 2.Department of Geosciences, Applied MineralogyEberhard Karls University of TübingenTübingenGermany
  3. 3.Institute for Archaeological SciencesEberhard Karls University of TübingenTübingenGermany

Personalised recommendations