See Quetzalcoatl. X-ray fluorescence spectrometry [XRF]. A technique of chemical analysis. Principle. An artefact (or sample, if the artefact is too large to fit inside the chamber of the machine) is irradiated with X-rays. Resultant changes within the atoms of the material cause secondary X-rays to be emitted back. The wavelengths of these secondary X-rays are determined by the elements present in the material. Thus, analysis of the secondary X-ray spectrum allows the concentrations of different elements to be calculated. A development of the technique is the X-ray Milliprobe, which focuses the beam of primary X-rays on a much smaller area, with the specimen outside a window in the chamber of the machine. This allows small areas of objects of almost any size to be examined. Materials. Since only the surface of the specimen is examined, the method is essentially non-destructive, although in some cases it may be necessary to use a powdered sample. The technique has been employed to examine glass (natural and man-made, including glaze), pigments, pottery and metals (in coins). Applications. XRF has been used to identify sources of obsidian artefacts, by analysing their trace elements and matching them with those of the sources of the material. The technique has also been used to characterize pottery from its minor and trace elements, and to investigate glazes on the surface of pottery. In its X-ray milliprobe form, the method has been employed for non-destructive analysis of major elements in coins and for examing decoration on the surface of glass beads. [Asm]. See ritual vessels (China).
The Macmillan dictionary of archaeology, Ruth D. Whitehouse, 1983Copied