Detecting the Use of Fuel with Autofluorescent Phytoliths

Summary

This is an abstract from the "SAA 2025: Individual Abstracts" session, at the 90th annual meeting of the Society for American Archaeology.

Phytoliths are often found in archaeological contexts associated with cooking and burning, and where plant material has been used as fuel. Different methods have been applied to identify whether phytoliths have been fired and/or heated: morphological alterations, changes in color and opacity, refractive index, and Raman spectroscopy. None provide satisfactory results for sufficient discrimination between burned and unburned phytoliths. We surveyed phytoliths from various archaeological contexts (unheated and heated), chronological periods (prehistoric up to the classical period), and geographical settings (temperate, subtropical and tropical). Our observations from archaeological material suggest that phytoliths become autofluorescent in heated contexts. Significantly, phytoliths that were not heated show no autofluorescence. Subsequent work attempted to explore the conditions under which autofluorescence occurs in the inflorescence bracts of oats (Avena sativa (L.)) when they are heated. Three factors were investigated: temperature, time, and the presence or absence of oxygen. Phytoliths fluoresced after 30 minutes, at temperatures as low as 200°C, and oxygen was not required for autofluorescence. This signal may then become an important proxy complementing the previously developed techniques. As such, integration of various proxies can provide a systematic and straightforward method to track evidence of fire and heating of phytoliths within archaeological contexts.

This Resource is Part of the Following Collections

• Society for American Archaeology 90th Annual Meeting, Denver, CO (2025)   •
• SAA 2025: Individual Abstracts

Keywords

Record Identifiers

Abstract Id(s): 53033