Ancient markets are difficult to identify as most utilitarian items and consumables were perishable. Our objective was to use geochemical analyses of extractable phosphorus and metallic residues in soils to distinguish market plazas from other types of plazas at the ancient Maya city of Seibal, Guatemala. Geochemical techniques in conjunction with locational and archaeological data have identified a marketplace at Chunchucmil, Mexico. We will report the results of extractable phosphate and metals from plazas A, C, and E at Seibal.