Microstructural and mineralogical analysis of Urysay-2 ceramics by X-ray microtomography and Raman spectroscopy

Abstract

The article presents the results of applying X-ray computed tomography (CT) to study the spatial arrangement, size distribution, and morphology of internal inclusions in several ceramic fragments from the Urysay-2 complex in the Zhambyl district of the Almaty region (Republic of Kazakhstan). Based on the tomographic data, segmentation of the internal inclusions was performed, and the grain size of the ancient ceramic samples was calculated. The reconstructions enabled a quantitative morphometric analysis of mineral inclusions, providing statistical distributions of equivalent diameter, elongation, and sphericity. The results revealed significant technological differences: sample C-1 contains the largest and most irregular inclusions (average equivalent diameter ≈ 0.35 mm, mean sphericity ≈ 0.90), whereas C-2 and C-3 show smaller and more uniform grains (average equivalent diameter 0.25–0.30 mm; sphericity up to 0.96), reflecting finer tempering. Raman spectroscopy identified the mineral phases of the samples, including quartz, albite, calcite, hematite, anatase/rutile, and magnetite. The anatase-to-rutile transformation observed in C-2 indicates firing temperatures above ~800 °C under oxidizing conditions. Beyond archaeology, this approach provides a reliable framework for the quantitative characterization of porous ceramics and composite materials in materials science.