Technological Reconstruction and Chemical Similarities of Fine Earthenware from the 18th and 19th Centuries Using EDXRF (State of Piauí, Brazil)

Tableware is a domestic object that reflects everyday socio-cultural activities, making it a valuable subject for archaeometric studies. This study aims to chemically analyze crockery fragments from the 18th- and 19th-century colonial period using portable energy-dispersive X-ray fluorescence spectrometry (pEDXRF) and chemometric treatment for technological reconstruction and chemical similarity assessment. Analysis of the paste and glaze revealed that SiO2, Al2O3, and CdO are the main constituents. Due to a CaO content of less than 6%, the paste was classified as non-calcareous clay. The presence of PbO2 and CoO in the glaze composition identified the dishes as fine pearlware, artifacts produced from the 18th century onward. Principal Component Analysis (PCA) defined affinity clusters only for the glazes, while a more specific analysis using a ternary diagram revealed two distinct groups for both pastes and glazes, differentiated by the presence or absence of cadmium. This finding highlights an atypical and unique characteristic of the analyzed samples, particularly given the significant Cd content identified.