A07_04

Scoop on Poop (or You Are What You Eat): Radiocarbon Examination of Linen and Fecal Material from a Coptic Textile

Cox J¹,  Rowe M¹, Blinman E¹, Jones S¹, Welte C^2,3

¹Office Of Archaeological Studies, Center for New Mexico Archaeology, Santa Fe, United States, ²Laboratory of Ion Beam Physics, ETH Zűrich, HPK, H29, Otto-Stern-Weg 5, CH-8093 , Zürich,  Switzerland, ³Geological Institute, ETH Zürich, NO, Sonneggstrasse 5, CH-8092 , Zürich,  Switzerland

A textile was provided to the Office of Archaeological Studies Plasma Oxidation Laboratory to determine if it was possibly of Coptic age. In the process of examining the material, feces of insect larvae (likely clothes moths) were found between the acrylic sheets that were placed on either side of the textile for preservation and presentation purposes. The insect infestation was relatively modern (within the last 15-20 years). The excrement stood out as the insects weren’t able to metabolize the dyes in the textile thus leaving blue and orange pellets.

A single linen fiber was chosen from the textile for dating purposes using an oxidizing plasma to collect enough CO₂ gas for dating before being sent to ETH-Zürich to be processed with a MICADAS AMS system. In addition, the fecal material was oxidized in an oxygen plasma. Multiple carbon samples were collected with no visible change of the fiber itself, but the pellets lost the surface dye color during the oxidation process, leaving the base linen color.

Regular cleaning procedures were followed with initial oxygen plasmas used to clean the chamber until <0.5 µg of carbon were present. This was followed by argon plasmas until <0.5 µg of carbon were present. Finally, oxygen plasmas were run to produce enough CO₂ for measurement purposes (20-100 µg carbon) to be analyzed at ETH-Zürich.

The agreement between the radiocarbon dates from the linen and the fecal matter indicate that no apparent modern day contamination occurred during the metabolization process of the larvae.