Energy Dispersive X‐Ray Fluorescence and Micro‐Computed Tomography Analysis of Ancient Pottery and Fragments From São Joaquim Archeological Site From Rio de Janeiro, Brazil

ABSTRACT This study presents an archeometric investigation of ceramic fragments and associated sediments recovered during archeological excavations conducted in 2018 at the base of the Church of São Joaquim (built in 1758), located in downtown Rio de Janeiro, southeastern Brazil. The assemblage, recovered near the high altar, included ceramic fragments, sediments, human remains, glass, stoneware and porcelain fragments, animal bones, keys, and smoking pipes. The spatial arrangement and preservation state of bowls, plates, and bottles suggest intentional deposition, consistent with ritual practices associated with African‐derived religions historically linked to the church. Ten samples, comprising ceramic fragments and sediments recovered from inside ceramic vessels, were analyzed using energy dispersive x‐ray fluorescence (EDXRF) and micro‐computed tomography (microCT) to characterize elemental composition and internal density variations. EDXRF results reveal a consistent elemental assemblage dominated by Al, Si, K, Ca, Mn, Fe, Ni, Cu, Sr, Zr, Ba, and Pb, with minor variations among samples. MicroCT imaging shows pronounced density heterogeneities, with low‐ to intermediate‐density matrices and localized high‐density regions, particularly near surfaces and interfaces. The combined interpretation of elemental and density data suggests the presence of compositionally heterogeneous sediments and surface‐enriched phases, potentially related to intentional material use, ritual residues, and post‐depositional environmental processes. These results contribute to a better understanding of material practices and ritual behaviors associated with the historical use of the Church of São Joaquim.