Archaeology

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. 

Lead alloys (50 mg for flame analysis, 10 mg for furnace atomisation) can be dissolved in 1ml of distilled water with 0.5 ml nitric acid added. After warming, 5 ml of concentrated hydrochloric acid is added to dissolve the tin content, any precipitated lead chloride may be removed by centrifugation. Nickel, silver, tin and zinc may be determined in this solution using a conventional air/acetylene flame. Silver is usually the element of most interest in lead, but the proportion of tin in pewter is significant. The lead content can be determined in the original nitric acid solution but it is difficult to measure tin and lead in the same solution. 

Silver alloys present similar problems and the silver content can be determined after dissolution of 5—10 mg in 1 ml of 50% nitric acid. The tin and gold present will appear as a black residue which may be taken up in 1.5 ml concentrated hydrochloric acid, which of course precipitates silver chloride. The precipitate is removed by centrifugation. Thus again two solvents are required to determine the normal range of elements, e.g. bismuth, copper, gold, lead, silver and tin. 

Iron is best sampled by drillings (10 mg) which may be dissolved in aqua regia (1 ml). Standards should be prepared in a similar way and conventional flame techniques then usually suffice. 

It seems likely that the range and scope of archaeological applications will continue to increase, particularly using graphite furnaces, and as the significance of more exotic elements, such as the lanthanoids and higher weight alkali metals, becomes apparent. 

Pattern recognition is a powerful tool in the identification of archaeological artefacts. A typical example of a pattern recognition application in chemistry is the classification of obsidian artefacts by Kowalski et. al. C1623. A total of 45 obsidian samples from different sources in northern California and 27 archaeological obsidian artefacts of unknown origin were analyzed by X-ray fluorescence spectroscopy. 

For each sample ten trace elements (Fe, Ti, Ba, Ca, K, Mn, Rb, Sr, Y, Zr) were determined in a concentration range of 40 - 1000 ppm. Each obsidian sample is therefore represented by a point in a 10-dimensional space. 

A similar technique of data analysis but without sophisticated pattern recognition methods was applied by Bird et. al. C19D. The concentrations of three elements (F, Na, Al) were determined by proton induced gamma-ray emission in 700 obsidian artefacts from 20 sources. Two-dimensional plots Al versus Na and F versus Na showed distinct clusters- 

Flint samples from four different mines and from prehistoric workshops were analyzed by neutron activation analysis to determine the contents of 14 trace elements. A successful separation of the four origins was possible by a Bayes classifier, by classification with centres of gravity, and by factor analysis C663. 

Potsheards were classified by hierarchical clustering using the concentrations of 14 trace elements determined by neutron activation analysis C2203. 

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Carbon has seven isotopes. In 1961 the International Union of Pure and Applied Chemistry adopted the isotope carbon-12 as the basis for atomic weights. Carbon-14, an isotope with a half-life of 5715 years, has been widely used to date such materials as wood, archaeological specimens, etc. 

A novel technique for dating archaeological samples called ammo acid racemiza tion (AAR) IS based on the stereochemistry of ammo acids Over time the configuration at the a carbon atom of a protein s ammo acids is lost m a reaction that follows first order kinetics When the a carbon is the only chirality center this process corresponds to racemization For an ammo acid with two chirality centers changing the configuration of the a carbon from L to D gives a diastereomer In the case of isoleucme for example the diastereomer is an ammo acid not normally present m proteins called alloisoleucme... 

One of the important advantages of NAA is its applicability to almost all elements in the periodic table. Another advantage of neutron activation is that it is nondestructive. Consequently, NAA is an important technique for analyzing archaeological and forensic samples, as well as works of art. 

Some solid materials are very intractable to analysis by standard methods and cannot be easily vaporized or dissolved in common solvents. Glass, bone, dried paint, and archaeological samples are common examples. These materials would now be examined by laser ablation, a technique that produces an aerosol of particulate matter. The laser can be used in its defocused mode for surface profiling or in its focused mode for depth profiling. Interestingly, lasers can be used to vaporize even thermally labile materials through use of the matrix-assisted laser desorption ionization (MALDI) method variant. 

A good LC/MS instrument routinely provides a means for obtaining the identities and amounts of mixture components rapidly and efficiently. It is not unusual to examine micrograms or less of materia). LC/MS is used in a wide range of applications, including environmental, archaeological, medical, forensic, and space sciences, chemistry, biochemistry, and control boards for athletics and horse racing. 

Other important areas of mass spectrometric investigation of isotope ratios need accurate, not approximate values. For example, for some investigations in archaeology, pharmaceuticals, and chemistry, very accurate precise ratios of isotope abundances are needed. 

Early scientific studies were ptedominandy aimed at objects often referred to as belonging to the fine arts. Subsequendy, equal importance and effort has been attached to studies of objects of cultural and historical interest, such as archaeological and ethnographic materials, or manuscripts, documents, photographs, and books in archives andUbraries. This article is meant to be inclusive of all such objects as well as of fine arts objects. The term art object when used is an inclusive, generic connotation rather than an exclusive one. 

Technological History. In the history of technology, the developments of metallurgy probably provide the most compHcated and important chapter. Although new archaeological evidence continually necessitates changes in accepted hypotheses regarding the developments in the use of metals in... 

Trace-element analysis, using emission spectroscopy (107) and, especially, activation analysis (108) has been appHed in provenance studies on archaeological ceramics with revolutionary results. The attribution of a certain geographic origin for the clay of an object excavated elsewhere has a direct implication on past trade and exchange relationships. 

Deteriora.tlon. Apart from physical damage that can result from carelessness, abuse, and vandaUsm, the main problem with metal objects Hes in thek vulnerabihty to corrosion (see Corrosion and corrosion control) (127,128). The degree of corrosion depends on the nature and age of the object. Corrosion can range from a light tarnish, which may be aesthetically disfiguring on a poHshed silver or brass artifact, to total mineralization, a condition not uncommon for archaeological material. 

On archaeological glass objects, layers of reaction products are formed and the main constituents of these cmsts are the less-soluble compounds such as siHca and calcium carbonate, which becomes calcium sulfate. 

Clearly, the intended use of a collection item is extremely important to determining the acceptabiHty of a treatment. The degree to which a treatment affects appearance is obviously of the greatest importance for an art object. On the other hand, in natural history collections the collections serve as research resources above all. The effect a preservation or conservation treatment has on these research appHcations is the main consideration. Collections of art, archaeology, history, science, technology, books, archival materials, etc, all have their own values in terms of balance between preservation needs and collections use, and these values are, moreover, constantly subject to reevaluation and change. 

E. V. Sayre and co-workers, eds.. Materials Issues in Art and Archaeology, Materials Research Society Symposium Proceedings Vol. 123, Materials Research Society, Pittsburgh, Pa., 1989. 

C. W. Beck, ed.. Archaeological Chemisty, Advances in Chemistry Series No. 138, American Chemical Society, Washington, D.C., 1975. 

M. J. Aitken, Science-based Dating in Archaeology, Longman, London, 1990. 

S. Frank, Glass and Archaeology, Academic Press, Inc., London, 1982. 

A. Porteous, Kefuse DerivedFuels AppHed Science Pubhshers, London, 1981 H. Alter, Kesource Rec. Conserv. 5(1), 1 (1980) W. Rathje and C. Murphy, Rubbish The Archaeology of Garbage Harpers Collins, New York, 1992. 

W. Rathje and C. Murphy, Rubbish The Archaeology of Garbage, Harpers Collins, New York, 1992. 

BC. Archaeological findings indicate its use in cloth in 3,000 BC, and there are records of its cultivation in India as far back as 700 BC. In the fifth century BC, Herodotus wrote of "trees" growing wild in India bearing wool of a softness and beauty equivalent to that of the sheep clothes made from this tree wool were described as garments of extraordinary perfection. 

N.V. Polosmak and V.A. Tmnova. An analysis of Pazyryk hair (X-ray fluorescent analysis using synclirotron radiation) //Archaeology, Ethnology Anthnoropology of Eurasia, 1(17) 2004, p. 73-71. 

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