A SEM-EDS Study of Cultural Heritage Objects with Interpretation of Constituents and Their Distribution Using PARC Data Analysis

Two cultural heritage objects studied with scanning electron microscopy-energy dispersive spectroscopy (EDS) are presented in this article: (1) archeological iron present in a soil sample and (2) a chip from a purple-colored area of an undisclosed 17th century painting. Novel PARC software was used to interpret the data in terms of quantitative distribution of mineral and organo-mineral phases as well as their chemical composition. The study serves to demonstrate the power of PARC rather than solving specific archeological issues. The observations on archeological iron potentially can assist in (1) studing the source of iron-metal and the style of forging, (2) learning about alteration processes of artifacts in the particular soil from which the sample originated, and (3) determining the nature of the fractures in the Fe-oxide envelope (desiccation of the sample after excavation, or as primary feature caused by volume change from oxidation). In the paint chip, 11 consecutive layers can be distinguished using the PARC software. In general, each layer consists of a carrier supporting inorganic fragments. In the basal layer the fragments are dominant; in the superimposed layers the carrier usually is. Both organic and inorganic carriers appear to be present. Organic carriers can contain typically inorganic constituents (e. g., Pb, Al), beyond the chemical spatial resolution of EDS (i. e., < 1 mu m).