2025/10/03 by Wei Zhao, Jingui Xu, Dongzhou Zhang +5 · 1 voice
Computer Science · Earth and Planetary Sciences · #Geochemistry and Geologic Mapping #Mineralogy and Gemology Studies
paper · pdf · doi:10.2138/am-2025-9856
openalex publication_date 2025/10/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
Abstract Rhodonite (MnSiO3) is a pyroxenoid with a single-chain silicate structure related to pyroxenes. In this study, we investigated the structural evolution of synthetic rhodonite up to 35.0(1) GPa using in situ synchrotron single-crystal X-ray diffraction. The results indicate that rhodonite retains its triclinic structure (P1¯) throughout the pressure range; however, it undergoes an isosymmetric second-order phase transition at 10.9(1) GPa, driven primarily by an increase in Mn coordination number. Contrary to earlier findings on amorphization, rhodonite retains its crystallinity up to 35.0(1) GPa. Moreover, this study also reviews the high-pressure phase transitions in orthopyroxenes, clinopyroxenes, and pyroxenoids, with a particular focus on mechanisms and characteristics of the structural phase transitions. Through comparative analysis, we have identified both commonalities and differences among these chain silicates. Specifically, we have further highlighted the crucial roles played by the rotations of tetrahedra, increases in coordination numbers, and the interplay between these factors in governing their phase transitions. These findings not only enhance our understanding of pyroxenoid structural evolution at high pressure but also provide valuable insights into chain silicate stability in the deep Earth.