Metals, archaeological materials analyses

Sampling. Concentrations of carbon in archaeological materials range from very large in charcoal to less than 1% in metals, foundry slags, and pottery. The size of the sample needed for analysis, thus, depends on the nature of the material as well as its age. The analytical procedure used to isolate the carbon may result in significant losses during extraction and chemical conversion. Samples should always be taken in sufficient quantity for replicate determinations and comparison with control specimens. 

Hoffmann, P. (1989). HPLC analysis of polyethylene glycols (PEG) in wood. In I. D. MacLeod (Ed.), Conservation of wet wood and metal, Fremantle 1987 Proceedings (pp. 41-60). ICOM Committee for Conservation, Working Groups on wet organic archaeological materials and metals. 

Neutron activation is not a widely used method (Fig. 17.8). Some of its applications include characterisation of materials (e.g. high purity metals, semiconductors), the study of the distribution of chemical elements within fossils, ultra-trace analysis in archaeology and geology, and the study of volcanoes. 

Atomic absorption is suitable for the analysis of several types of ancient inorganic materials, e.g. metals and alloys, silicates and minerals. Only a few milligrams of sample are required typically 10 mg may be dissolved in 25 ml for analysis. Electrothermal methods may require even less sample and are thus very attractive in this field. Often papers describing results obtained by atomic absorption give little or no analytical details. Table 4 lists some of these publications to illustrate the potential scope of atomic absorption spectrometry in archaeology, but the review of Hughes et al. [210] remains the best source of experimental detail. 

X-ray fluorescence analysis had been used for composition studies of various materials. Probably among the most important applications are research on metals and on inorganic pigments. Analyses similar to the ones I quoted are very helpful in authenticity studies and can aid the cosmetic industry, metallurgy, and so on. The demands archaeological chemistry made (nondestructiveness, small sample size, quick analysis, sensitivity) has helped significantly to develop x-ray fluorescence instrumentation. 

It is clearly desirable to minimize the amount of material withdrawn from an archaeological sample for analysis. In some cases it has been possible mechanically to shear off slivers of metal that can serve directly as electrodes. In other cases the material is somewhat granular but can be compressed in a die to form cohesive electrodes. However, under many circumstances there is no alternative to melting and casting, and for this the apparatus shown diagrammatically in Figure 2 was developed. 

Atomic absorption spectrometry (AAS) has been extensively employed in the analysis of metallic and siliceous materials of archaeological and art historical significance. The scope and practical aspects of the technique of relevance to archaeology were comprehensively reviewed in 1976 (J) a more recent report focused on the application of atomic absorption analysis to archaeological ceramics (2). The technique carries the potential for analysis of a wide range of elements with good... 

---