MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDlNGS VOLUME 462 Materials Issues in Art

Thirty-four gold solidi coins and two pairs of gold/jewel earrings were discovered at an archaeological site in Jordan, Tell Nimrin. The coins have stamped images of six late Roman/early Byzantine emperors who reigned from 346 AD to 518 AD. These objects were analyzed by X-ray radiography, SEMEDS and density measurements to fmd the gold content for comparison with other coins of that period to support their authenticity and to see whether debasement of coinage had occurred. The average surface gold content was found by EDS to be 98. I wt %--typical of the period--but the bulk content calculated from density values was 1 to 3 wt % lower. The reason offered is that when a molten gold-copper or gold-silver alloy solidifies, the region in contact with the blank coin mold freezes first and is gold-enriched. Small “silvery” specks were observed on the obverse (“heads”) side of several coins and found by EDS to be Os-Ir-Ru alloys, which come from placer mining and indicate that the gold also came from placer mining