Synchrotron tts-µXRD identification of secondary phases in ancient ceramics

Abstract

The study of the alteration process, and in particular of secondary phases precipitated in pottery after its production, can constrain the post-depositional environments or the type of use of the pottery. Detailed study of secondary phases can be done using different approaches, based on microscopic, microstructural and microchemical analyses, as well as mineralogical methods. In the present study are reported the results of the application of punctual mineralogical analysis by synchrotron through-the-substrate microdiffraction (tts-μXRD) to analyse secondary phases precipitated in ancient pottery (Bronze Age pottery form Frattesina in Italy and Mesolithic pottery form Al Khiday in Sudan). Although the chemical composition of these secondary phases in many cases almost matches with the stoichiometric composition of a known mineral, only some of them were actually true mineral phases (i.e. with crystallinity and therefore showing diffraction peaks), while others were amorphous. Some phases, the occurrence of which was previously attested only on the basis of their chemical composition (determined by scanning electron microscope or the electron microprobe analysis), were univocally identified as true vivianite (Fe 3 (PO 4) 2 •8H 2 O) and crandallite (CaAl 3 (PO 4) 2 (OH) 5 •H 2 O) minerals. Part of the phases detected in studied pottery, the chemical composition of which was consistent with specific mineral phases, were instead amorphous. The synchrotron through-the-substrate microdiffraction (tts-μXRD), therefore, represents a valid method for properly determine the mineralogical nature of secondary phases in pottery, as well as other small-sized and rare mineral phases occurring in polycrystalline materials of archaeological interest, such as pottery, mortars, painting and glassy materials.

Vivianite and Its Oxidation Products in Mammoth Ivory and Their Implications to the Burial Process

“…This process is accompanied by color changes from blue to bluish green then to yellowish brown . In archeology and geology, researchers can judge the sedimentary environment and the formation process of vivianite on the basis of the spatial distribution of vivianite and its oxidized products. − According to the chemical composition and oxidized degree of vivianite, some scholars speculated the origin and preservation integrity of works of art. ,, …”

Combination of Two Synchrotron Radiation-Based Techniques and Chemometrics to Study an Enhanced Natural Remineralization of Enamel

“…Therefore, this technique enables data collection directly on thin tooth sections preserving the textural context and allowing local identification of mineral phases. 14 …”

“…The synchrotron through-the-substrate micro X-ray diffraction (tts-μXRD) used in the present work allows performing punctual analysis in thin sections with a spot size of few micrometers. Therefore, this technique enables data collection directly on thin tooth sections preserving the textural context and allowing local identification of mineral phases …”

“…Therefore, this technique enables data collection directly on thin tooth sections preserving the textural context and allowing local identification of mineral phases. 14 There are several factors that put oral health at risk, such as the popularity of whitening systems with their side effects or the excessive consumption of acidic foods and beverages. 15−18 Demineralization caused by regular exposure of the tooth enamel to acids, such as those produced within accumulations of bacterial plaque from dietary carbohydrates, removes mineral ions from HA crystals and may cause a caries lesion.…”