New Data on Sources of Obsidian Artifacts from Tikal, Guatemala

Abstract
In 1984, 29 obsidian artifacts and an unworked nodule from Tikal were attributed to source by visual means and then analyzed by X-ray fluorescence (XRF). We conclude that the considerable within-source optical variability of gray Mesoamerican obsidians makes visual sourcing unreliable at present, although a corpus of descriptions of the optical characteristics of obsidian may eventually provide a way to exclude possible sources. The XRF analysis identified two additional central Mexican sources, bringing to six the number of Mexican obsidian sources represented at Tikal; failed to provide a secure identification for the nodule; supported the succession of Guatemalan obsidian sources utilized by the Southern Lowland Maya previously proposed by Nelson; and suggested other correlations between source, artifact type, and archaeological context.