Analysis of burnt bone by Alison Nicholson Session 9 2012
Analysis of burnt bone:Discovering the circumstances of burning
Why study burnt boneMany UsesUse of fire in prehistory, dietary and cooking habits, animal sacrifices, migration and trade in life stock, firing of cities, cannibalism, witch executions and funerary practises2 Questions• What are the bones?• What are the circumstances of burning?
What are the Circumstances of burning• Temperature• Time• Soft tissue• Oxidation• Other objects (metals)• Location
Analysis techniques• Colour• Fracture patterns• Elemental analysis (ICP-MS/XRF)• Other analytical techniques (XRD,FTIR, electron microscopy)• Use of external clues
Colour & TemperatureStage Temperature range Colour description Munsell (dominant colour)1 20-285 °C Neutral white/ pale yellow 5Y 8/2, 10YR 8/42 285-525 Reddish brown, dark grey brown, neutral N 2.7 5/0 dark grey, reddish yellow 7.5YR 8/33 525-645 Neutral black, medium blue, some reddish 10YR 7/2 yellow4 645-940 Predominately neutral white, with light N 9/0 blue grey and light grey N9.5/05 940+ Neutral white with some medium grey and N9.5/0 reddish-yellow
Colour & Metals• Characteristic colour for each metal:e.g.• Bronze: Green/Blue• Iron: Red• Zinc: Yellow
Problems with colour analysis• Secondary change• Many confounding variables
External clues• The melting of another material with a known or calculable melting point• E.g. Glass melts at 500°C to over 2000°C depending on the type of glass
Elemental analysisUse: Examples:• Identification of • XRF compounds or elements • ICP-MS• Good at detecting staining- Metals/ minerals• Thermal decomposition
Other analysisUses ExamplesDistinguishing burnt from • XRD unburnt • FTIRLooking at the degree of • Electron Microscopy burning:• Recrystallization• Thermal decompositionPenetration of staining
BibliographyShipman, P., Foster, G. and Schoeninger, M. (1984). Burnt Bones and teeth: an experimental study of colour, morphology, crystal structure and shrinkage. Journal of archaeological science, 11, pp.307-325Harter, R.(2011). Piltdown man. http://home.tiac.net/~cri_a/piltdown/piltdown.htmlNicholson, A.(2011). The effect of multiple burning on bone mineral
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.