Archaeometry

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  • Created by: ktommo
  • Created on: 21-05-17 18:46
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  • Archaeometry
    • Archaeometry is the scientific analysis of archaeological materials.
      • Laboratory analysis of finds can discover all sorts of information including composition, structure, date and in the case of artefacts, manufacturing information.
    • DNA Analysis
      • Where a set of DNA mutations are inherited they are called haplotypes.
      • The identification of haplogroups, people sharing a particular mutation, is used to trace the movement of population groups, for instance the spread of farmers across Europe during the Neolithic.
      • This technique is also used on crops and domestic animals, most of which have been traced back to their area of origin by comparing modern and ancient gene pools for different parts of the world.
      • Some mutations survive because they provide an evolutionary advantage.
    • Characterisation Studies
      • Scientific analysis of artefacts and building materials can reveal their chemical make-up.
      • Each stone or metal ore is extracted from a different geological location and within different geological situations.
      • Trace elements-stone or metal ore contains slightly different combinations and quantities of 'impurities'.
      • Where we know the geological sources of metal, clay or stone, archaeologists can normally identify the location that the materials came from.
    • X-Ray Fluorescence.
      • One of the cheapest and quickest methods of analysing the surface composition of materials. (mostly metal and pottery glazes)
      • Non-destructive
      • A beam of x-rays forces the material to re-emit x-rays. The intensity of the energy given off can be measured to indicate the chemicals present and how much there is of each.
    • Optical Emission Spectrometry
      • A range of methods which use radiation to force a small sample of material to produce light which can be measured through analysis.
      • This is a very accurate method and only requires small samples. This makes it suitable for valuable material.
      • It is widely used for metal analysis, but it is also used for glass, faience, pottery, obsidian and occasionally flint.
    • Atomic Absorption Spectrometry (AAS)
      • AAS is more precise than optical emission spectrometry, but is a slower process.
      • A minute sample is dissolved in acid and then vaporised.
      • When light of a known wavelengths is passed through the gas created, the amount that is absorbed indicates what minerals are present.
      • AAS is widely used for bronze and copper can can even analyse flint.
      • However it is destructive and this technique does not work if metal artefacts are made from several different sources.
    • Neutron Activation Analysis (NAA)
      • The most accurate and reliable characterisation technique and can be used on liquids and gases as well as solids.
      • Non-destructive
      • Tiny samples are ground down into a powder and heated to remove moisture and carbonate.
      • It is a useful technique for a wide range of materials, particularly coins.
      • However it is very expensive, with the analysis of a single sample costing over £100.
    • Isotope Analysis
      • By determining what isotopes are present, and in what proportions, materials can be linked to the places they came from.
      • Another major application of isotopes has been in identifying the sources of minerals in human and animal remains in order to study diet or population movement.
      • Particular combinations of isotopes are only found in specific geographic areas.
      • Variations in oxygen isotopes which humans acquire from local rainwater during childhood become locked into teeth enamel.
      • This technique has been used to identify the origins of both the Amesbury Archer and Otzi.
    • Carbon Isotopes in the food chain
      • Plants absorb carbon into their cells during photosynthesis.
      • When plants are eaten by other creatures, the carbon passes up the food chain, but the ratio between isotopes remains constant.
      • Carbon from bone collagen, tooth enamel or hair can be analysed using mass spectrometry.
    • Organic Residue Analysis
      • Far more residue including fats and sugars get absorbed into the fabric of unglazed vessels, usually during cooking, and survive intact.
      • Researchers have identified a series of 'biomarkers' which mark different lipids and can be traced to particular sources.
      • However the process is destructive
        • Following surface cleaning, a few grams of pottery are ground to a powder and mixed with chemical solvents and reagents to dissolve and extract the lipids.
        • Individual lipids are also not specific to one foodstuff and can potentially be introduced to the vessel at any stage of use.
        • Lipids are also present in human faeces and skeletons.
      • Although expensive, this technique can be used to answer a wide range of archaeologist's questions.

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