Pointing at fossils: pXRF identification of a fossilized shell projectile point. (February 2020)

• Record Type: Journal Article
• Authors: Scharlotta, Ian; Daniels, James T.
• Is Part Of: Journal of archaeological science. Volume 29(2020)
• Publication Date: 2020-02
• Subjects: Fossil shell -- Projectile point -- pXRF -- California; Archaeology -- Periodicals; Archaeology -- Research -- Periodicals; 930.1
• DOI: 10.1016/j.jasrep.2019.102184
• Languages: English
• ISSNs: 2352-409X

Abstract

Highlights: A unique shell artifact was compared with shell tools and unmodified reference materials. Differential chemistry identified that it was formed from a fossilized piece of shell. IS conducted the analysis, research, and wrote the manuscript with editorial feedback from JTD. J.T. Daniels provided access to the pXRF equipment, helped with analysis, and data processing. Abstract: A shell artifact recovered during wet-screening of cultural sediments from CA-SDI-39 (San Diego, CA) had several unusual properties. Fashioned into a triangular projectile point using lithic flaking techniques, the artifact was unlike any other shell tools in the associated assemblage or reported elsewhere in California. Unlike other shell tools in the assemblage, the artifact was not flakey, and appeared to have been formed from a very large shell. This combination of characteristics suggested possible origins from fossilized shells in Pliocene-Pleistocene aged marine terraces. Destructive sampling was not possible, so pXRF was used to investigate chemical evidence for fossilization, or other possible treatments. Results suggest that this artifact was formed from shell that formed under substantially different water conditions than present, evidencing recrystallization consistent with fossil or subfossil shell, but an incomplete mineral conversion.