A Compositional Analysis of Plain Ware Pottery from Pueblo la Plata and Richinbar Ruin, Agua Fria National Monument, Arizona

Temper analysis of plain ware ceramics from Pueblo La Plata indicates that none of the pottery contains local sand. La Plata is located atop Perry Mesa in central Arizona, where basalt dominates the geology. Petrographic thin-section analysis confirmed the observation that basalt was not present, thereby implying that the tempering materials used to make the pottery were not locally obtained. Unless local potters went far afield to procure their temper, the pueblo residents probably obtained their pots from non-local sources. The petrographic work in conjunction with clay chemistry assays with an electron microprobe suggest that the pottery may derive from at least two sources: one associated with sand containing numerous mafic grains, and another in which mafic grains are few or absent.