This study considers the chemical alteration of archaeological freshwater shell above the water table at Lyon's Bluff, located in east-central Mississippi, changes in trace element concentrations between unfired and fired shell, and the effect bacteria have on archaeological freshwater shell. Thin-section petrography, X-ray diffraction, cathodoluminescence, and scanning electron microscopy were conducted on archaeological shell from four layers from Unit 20N20W, with a depth of 80 cm spanning 450 years. ICP-MS analysis was also conducted on a modern freshwater shell. Results of the microscopy indicate pristine crystal structure. ICP-MS data show that certain trace elements within the shell maintain their concentration after firing at 500°C. The broader implications are: 1) that diagenetic alteration does not hinder chemical sourcing of shell at Lyon’s Bluff, and 2) that certain trace elements are more reliable than others, namely Sr2+, Al2+, Ba2+, and Mn2+, when conducting provenance studies on shell temper.