Bone tissue is a natural composite material consisting of organic components (collagen and calcium citrate) and a mineral phase (bone apatite). Infrared spectroscopy and X-ray diffraction are used to study structural changes in the mineral phase of the cortical bone tissue from Wistar laboratory rats during heat treatment in a temperature range of 50–400 °C with a heating step of 50 °C and an exposition time of two hours. It is shown that the nature of bone apatite transformations is correlated with the decomposition of organic bone tissue components (collagen and calcium citrate) at different heating stages. Changes in the bone apatite structure are recorded upon heating above 150 °C as a decrease in the half-width of the peak (310) in an XRD pattern and a decrease in the width of the absorption band at 604 cm–1 in the IR spectra. This change is associated with the transition from monoclinic to hexagonal modification and the disappearance of the mosaic structure of bone apatite mineral plates. Upon heating above 300 °C, further transformations of bone apatite are related to the change in the width of the 604 cm–1 absorption band causing by citrate ion to carbonate ion conversion, which leads to a decrease in the distance between adjacent mineral plates and their adhesion. Our data on the transformation of bone apatite during heating are important for the understanding the thermal stability of bone tissue and can be used in the elaboration of technologies for producing biosimilar materials for bone implantology.
Keywords: bone, bone apatite, heating, collagen, citrate, X-ray diffraction, IR spectroscopy.
Funding. This study was supported by the Ministry of Science and Higher Education of the Russian Federation (project no. FSWM-2025-0015) and Russian Academy of Science (project no. 0284-2021-0004).
Acknowledgements. The analytical studies were conducted using the equipment of the Center for Collective Use “Analytical Center of Geochemistry of Natural Systems” at the Tomsk State University (Tomsk, Russia). IR spectroscopic studies were performed at the Center for Collective Use of Isotopic and Geochemical Studies at the Vinogradov Institute of Geochemistry, Siberian Branch, Russian Academy of Sciences (Irkutsk, Russia). We are grateful to A.A. Shiryaev and S.M. Aksenov for the productive discussion at the XV All-Russian Scientific Conference “Minerals: Structure, Properties, and Analytical Methods”, which helped to improve this work. We are grateful to the reviewer E.V. Sokol and editors of the journal for valuable comments that helped significantly to improve this work.
Conflict of interest. The authors declare that they have no conflicts of interest.
Author contribution. A.A. Bibko, R.Yu. Shendrik, O.V. Bukharova– conceptualization, investigation;
R.Yu. Shendrik, M.O. Khrushcheva– analytical work; A.A. Bibko, O.V. Bukharova, R.Yu. Shendrik, M.S. Antonov, D.V. Lychagin– writing the manuscript, visualization, editing the final version of the manuscript. All the authors approved the final version of the manuscript prior to publication.
For citation: Bibko A.A., Shendrik R.Yu., Bukharova O.V., Antonov M.S., Khrushcheva M.O., Lychagin D.V. Two stage reorganization of bone apatite during heating. Mineralogy, 12(1), 105–118. https://doi.org/10.35597/2313-545X-2026-12-1-6.

Received 24.11.2025, revised 19.12.2025 accepted 20.03.2026

Artem A. Bibko – Junior Researcher, National Research Tomsk State University, Tomsk, Russia; bibko.geology@gmail.com
Roman Yu. Shendrik – Cand. Sci. (Phys.-Math.), Senior Researcher, Vinogradov Institute of Geochemistry SB RAS, Irkutsk, Russia;
Oksana V. Bukharova – Cand. Sci. (Geol.-Mineral.), Assistant Professor, National Research Tomsk State University, Tomsk, Russia; 
Maksim S. Antonov – Student, National Research Tomsk State University, Tomsk, Russia
Maria O. Khrushcheva – Cand. Sci. (Geol.-Mineral.), Researcher, National Research Tomsk State University, Tomsk, Russia; mashsa2904@mail.ru
Dmitry V. Lychagin – Doct. Sci. (Phys.-Math.), Head of the Department, National Research Tomsk State University, Tomsk, Russia

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