24. X-raying Antiquity
Robert Thorne, Physics, and Kevin Clinton, Classics, have demonstrated with research colleagues a method of recovering 2,000-year-old faded text inscriptions on ancient stone using x-ray fluorescence imaging at the Cornell High Energy Synchrotron Source (CHESS). The researchers applied a nondestructive chemical analysis technique. CHESS’ intense x-ray beam was fired at three inscribed marble stones, on loan from the Columbia University’s Butler Library, revealing trace-element measurements and producing a map of each element’s concentration. The chosen inscription—one in Greek and two in Latin—showed different levels of wear. X-ray fluorescence (XRF) imaging detected minute amounts of iron, zinc, lead, and other elements in the inscribed regions. Usually, iron chisels were used to inscribe the stones, and the letters were painted with pigments containing metal oxides and sulfides. In the most worn stone, the trace elements measured by x-ray fluorescence clearly revealed the contours of the original letters, even where they were no longer visible to the eye. For modestly worn stones, XRF imaging will help to decipher texts and may provide new information on how the inscriptions were made. This was the first successful application of XRF imaging to the study of ancient stone inscriptions between 1,800 and 2,400 years old. Inscribed texts are invaluable to linguists, philologists, historians, archaeologists, art historians, and those who study the ancient world. XRF imaging has the potential to become a major tool in epigraphy.