Elemental variation in prehistoric Unionoida shell: Implications for ceramic provenance

As part of ongoing efforts to refine ceramic-provenance methodology, we examine the universality of freshwater mussel shell chemistry as reported in an earlier study. We find that samples of prehistoric shell from several locations in eastern North America are chemically distinct from the modern sample of shell from Missouri that was previously used to develop a formula for adjusting elemental abundances in shell-tempered pottery. The observed elemental differences may be attributable to the use of prehistoric versus modern shell, or they may relate to watershed-specific geological chemistry. Regardless of the source of these differences, we suggest that future provenance studies involving shell-tempered wares would be well served by complementary analyses of locally derived prehistoric shells to better the effects of shell tempering on ceramic chemistry.