An Analysis of pXRF Obsidian Source Attributions from Tikal, Guatemala

Abstract

Portable X-ray fluorescence spectrometry (pXRF) was used to obtain source determinations for 2,235 obsidian artifacts. These were supplemented by 48 previously published results made by X-ray fluorescence spectrometry (XRF) and instrumental neutron activation analysis (INAA) to bring the total sample to 2,283. Thirteen geological sources have been identified by instrument to date. Three sources in Highland Guatemala accounted for nearly 98 percent of all attributions, with approximately 2 percent from 10 green and gray obsidian sources in central Mexico. Geological sources can be brought into cultural context by examining their distributions among types of artifacts, recovery contexts, structure group types, distance from the Classic period epicenter of the city, and chronological relationships. Several procurement systems operated to import obsidian cores and other artifacts. Consumers obtained obsidian artifacts primarily through marketplace exchange, but other kinds of distribution are also indicated. The reliability, portability, rapidity, ease of use, non-destructive nature, and relatively low cost of pXRF show promise for the acquisition of the source attributions needed to construct the past cultural contexts of obsidian procurement and use. This method produces results comparable to those obtained by other kinds of instrumental analysis, and with a considerably higher degree of reliability than visual determinations.