Materials, archaeological sizes

In a similar manner to SAXS, microfocus X-ray fluorescence analysis can be targeted at small spot sizes and this can be linked to visual analysis of the archaeological thin-section. Figure S shows an example from the Kongshavn archaeological site in Finnmark, Norway (33). Here maps of elemental distributions (Figure Sb, Sc) can be linked visually to the assemblage materials... 

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. 

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. 

Atomic absorption sample preparation procedures applied to archaeological samples can be streamlined. Important factors include sample preparation, sample size, sample decomposition, standards, instrumentation, and practical and conceptual applications of atomic absorption analysis. On a comparative basis the sample preparation procedure reported was convenient and rapid the AAS instrumentation proved to be flexible, sensitive, rapid, and inexpensive in the analysis of archaeological materials. 

The range of raw materials that humans use for food, construction, valuables, transportation, and other purposes is enormous. Many materials are found at archaeological sites. The Black Earth site in southern Illinois, a settlement of hunters dating from 4000 to 3000 bc provides an example. It is an enormous site, more than a city block in size, and the cultural layer is up to 1.5 m (5 ft) deep. The concentration of ash, excrement, and other organic matter in the sediments changed the chemistry of the soil, resulting in more alkaline conditions, favorable for the preservation of bone and other materials. 

Elemental analysis, determination of the chemical composition of material, is the most common type of analysis in archaeological chemistry. A variety of instruments can be used for such analyses including SEM microprobes, ICP spectrometers, mass spectrometers, CN analyzers, NAA analysis, and many others. The instruments chosen for elemental analysis depend on several factors including availability, elements of interest, the nature and size of sample, cost, turn-around time, and others. A variety of materials have been investigated with elemental analysis, almost any kind of archaeological material that exists. 

There is considerable variation among instrumental techniques in their ability to measure specific elements. But ideally any instrument designed for elemental analysis, with adequate sensitivity, precision, accuracy, and proper calibration can be used. Important concerns in instrumental analysis also include the demands of sample preparation - whether a technique is destructive - and the size and quality of the sample needed. Many types of instruments require a powder or liquid sample that involves destructive preparation. Archaeological materials are turned into powders for NAA and XRD, liquids or solids for ICP-MS, and gas for GC-MS. But rare, significant, or unusual specimens cannot be destroyed for analysis. A few instruments with larger sample chambers can perform nondestructive analyses. There are also new techniques, such as LA, that cause very little damage to the sample. 

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