UC Davis researchers have developed what they believe is the firstcompletely nondestructive method for identifying the geological source of certain artifacts. The new approach provides a rapid and inexpensive solution to the problem of the chemical fingerprinting of artifacts manufactured from a common type of volcanic rock known as basalt. Based on the popular X-ray fluorescence spectrometry technique, the new method was developed as a result of a chance meeting between Thomas S. Latham, a graduate student in geology, and Paula A. Sutton, a graduate student in anthropology, according to UC Davis geology professor Kenneth L. Verosub. Latham had been mapping and analyzing lava flows in the Truckee area, just north of Lake Tahoe. Sutton had been studying a collection of artifacts from the same area. Sutton asked Latham if he could help her determine the sources of the artifacts. Even to the trained eye of a geologist, different lava flows in the area look virtually identical. Prior to the new work, the only way to identify the basaltic lava used for manufacturing an ancient stone tool involved either grinding samples of the artifact to a powder for X-ray and other chemical analyses or subjecting it to radiation that lingered after the test. The new way combines modern X-ray data with a 2,500-year-old mathematical formula to identify the ratios of trace elements in artifacts. Those ratios can be compared with the trace element ratios of individual lava flows. In a study published in a recent issue of the international journal Geoarchaeology, Verosub, Latham and Sutton report that their new technique indicates that many of the tools at Sutton's site came from a single lava flow.