Microanalysis of Taphonomic Alteration on Skeletal Material - A Novel Approach to Identifying Damaging Sulfur Compounds

Summary

The geochemistry of taphonomic alterations affecting buried bone has been little studied, yet has vast implications for scientific interpretation of archaeological and paleontological specimens in a world now embracing chemical methods in geoarchaeology. This investigative study of black surface staining on mammalian sub-fossil bone excavated from the bed of the Santa Fe River in northern Florida exemplifies the need to carefully evaluate post-depositional alteration. Such stains typically are attributed to secondary mineralization of manganese oxides, however microanalysis revealed no evidence for manganese but instead identified crystals of pyrite within a thick red and black banded stain, identified as iron oxide and a ferric tannate complex respectively. Based upon multiple analytical methods, reaction mechanisms are proposed. This study debuts a novel sample preparation method for high-vacuum analysis of bone material, and demonstrates a cost-effective method to differentiate between damaging pyrite and other inert sulfur compounds in specimens. Results indicate that fossil coating types are extremely dependent upon the chemistry of the environment in which they are buried. Further, it is proposed that staining phenomena affecting fossils may pose risk to collections if not properly identified, treated, and curated.

This Resource is Part of the Following Collections

• Society for American Archaeology 83rd Annual Meeting, Washington, DC (2018)

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Record Identifiers

Abstract Id(s): 20264