Arnb. arch. eplg. 1996: 7: 75-81 Printed in Denmark. All rights reseroed Copyright 0 Muwksxaard 1996 Arabian archaeology and epigraphy ISSN 0905-7196 A Trial PIXE/PIGME analysis of Pre-Islamic Arabian Coinage PETER GRAVE', ROGER BIRD2 AND D.T. POTTS3 'N.W.G. Macintosh Centre for Quaternary Dating, The University of Sydney, N.S.W., Australia; 2Australian Nuclear Science & Technology Organisation, Lucas Heights, N.S. W., Australia; 3School of Archaeology, The University of Sydney, N.S.W., Australia Eight previously published (1) pre-Islamic coins minted in Arabia were sub- jected to non-destructive ion beam analysis by Proton Induced X-Ray (PIXE) and Gamma-Ray Emission (PIGME) at Lucas Heights. The results (2) were interpreted using Principal Components Analysis (PCA). The relative X-ray in- tensities of fifteen elements, supplemented with additional L alpha lines for two of the elements, were extracted for this analysis. PCA (results appended) was first carried out on the whole dataset where the distinctive high iron and nickel composition of two coins (331 and 335) resulted in their position as out- liers. A second analysis of the subset of silver coins showed the compositional similarity between four coins (44, 222,226, 359) and distinguished two separate outliers. One of these (369)has a high lead and tin content while the other (354) has a greater proportion of elements present as impurities (?) including iron and nickel. The two outliers and the relatively homogenous compositions of the group of four coins suggest that three compositional types of silver coinage are represented in the dataset: 1. a relatively silver-rich group of four coins; 2. silver coins debased with lead; and 3. silver coins debased with iron and nickel. Introduction The origin of a coin is very often defined by its size, shape, design and legend. Meas- urement of its chemical composition then helps to establish details of minting pro- cedures as well as economic conditions as- sociated with specific regimes and periods of history. Although large numbers of coins have survived from ancient times, their value to historians and collectors is such that non-destructive methods of analysis are clearly preferable. On the other hand, corrosion and contamination introduce problems for many non-destructive tech- niques such as X-ray diffraction and ion- beam analysis which analyse only a surface layer. Such problems are largely overcome, however, if a small area is cleaned, allowing for the determination of major, minor and some trace elements. When historical information is not avail- able to establish the location of mints and the interpretation of coin designs, non-de- structive analysis by the PIXE / PIGME technique provides valuable information which can help in grouping coins and in- vestigating other numismatic factors, all of which can contribute to a better under- standing of the historical and archae- ological significance of the material. For many years, there has been an obvious in- terest in the non-destructive analysis of an- cient coins, but such analyses have largely been confined, in classical studies, to 75