Synchrotron applications in archaeometallurgy: Analysis of high zinc brass astrolabes

Abstract

Synchrotron X rays were used to perform nondestructive transmission diffraction and fluorescence experiments on a group of 24 European and Islamic astrolabes dated between 1350-1720 A.D. in order to determine their compositions. A group of six astrolabes produced in Lahore between 1601-1662 A.D. were found to contain a mixed ␣ϩ␤ brass microstructure, proving that the brass was produced by a comelting technique rather than the traditional cementation process. The results also show evidence of dezincification, attributed to heavy annealing of the brass during astrolabe manufacture. This effect was so severe that an accurate analysis of the bulk Zn composition could not be determined from the fluorescence results alone; transmission X-ray diffraction gives a more accurate measurement of the bulk Zn composition. © 2004 International Centre for Diffraction Data.

Synchrotron radiation-based x-ray analysis of bronze artifacts from an Iron Age site in the Judean Hills

“…Thus, the fluorescent x-rays were more heavily absorbed by the sample, such that they probed only the near-surface region on the incident beam side (up to w100 mm) while diffracted x-rays probed the entire sample thickness. The experimental setup is similar to previous archaeometric experiments using synchrotron radiation at the Advanced Photon Source (see Newbury et al, 2004;Stephenson et al, 2001;Young et al, 2006).…”

“…Furthermore, by working with high-energy (here E ¼ 80 keV) x-rays, one can penetrate beneath the surface of the artifact (i.e. at least one centimeter into leaded bronze), without surface removal, and at the same time leave no residual effects (De Ryck et al, 2003;Newbury et al, 2004;Stephenson et al, 2001;Young et al, 2006). In addition, the allowance for variability in the size of the specimens with little or no sample preparation makes these experimental methods ideal for archaeological materials.…”

“…Harbottle predicted that synchrotron radiation based x-ray techniques could be manipulated to serve all of these purposes with little or no sample preparation (Harbottle et al, 1986). In recent years, synchrotron radiation-based techniques have been used with increased frequency to study archaeological materials from museum collections and archaeological excavations (De Ryck et al, 2003;Grolimund et al, 2004;Harbottle et al, 1986;Janssens et al, 2000;Kockelmann et al, 2000;Newbury et al, 2004;Pinheiro et al, 2003;Schreiner et al, 2004;Stephenson et al, 2001;Young et al, 2006). In this study, synchrotron x-ray diffraction and x-ray fluorescence were employed to examine seven bronze bangles from Tell en-Nasbeh, northern Judah, to determine the phase composition, manufacturing process, and possible provenance of the artifacts.…”

Multi-analytical approach for an archaeometric study on orichalcum coins

“…The crucible was than filled with copper and covered with other charcoal and, once the cementation reaction had completed, it was heated to the temperature necessary to melt and homogenise the vessel content (Bayley, 1998;Bayley & Rehren, 2007;Tylecote, 1992). With this method, the weight percentage of the zinc in the alloy unlikely could exceed 28-30% (Bayley, 1998;Newbury et al, 2004;Rehren, 1999;Thornton, 2007), although higher zinc values are attested (Bourgarit & Bauchau, 2010;Di Fazio et al, 2019).…”

Complementary analytical methods for analysis of Ag-plated cultural heritage objects

“…It should also be noted that both XRD and XRF can now be performed in situ using portable devices and both have become common practices in the analytical study of cultural heritage objects [40][41][42][43][44][45][46]. Studies on the base material can be performed non-destructively using synchrotron, neutron, and proton sources available at large user facilities due to their much greater penetration depths; however, it is difficult to examine large bodies of work due to the nature of these facilities [47][48][49][50][51].…”