Retrospective of chrysotile synthesis: From tough geoinspired process up to soft chemical design

Chrysotile, the fibrous form of serpentine, is characterized by the chemical formula Mg3Si2O5(OH)4. Over the past seventy years, significant research has focused on synthesizing chrysotile, initially for petrological studies and more recently for applications in nanotechnology, particularly high-purity chrysotile nanotubes and doped variants. Common synthesis methods involve hydrothermal reactions using cristobalite and periclase or magnesium hydroxide and silica gel mixtures. Most frequently used synthesis conditions generally include temperatures between 200 °C and 400 °C and pressures from 0.5 to 100 MPa, though these often result in impure chrysotile with unwanted phases. Despite the promise of doped chrysotile, natural fibers are often unsuitable for nanoscience due to foreign ions and mineral intergrowths. Recent studies explore the potential for creating isomorphic series as Mg3Si2O5(OH)4 – Ni3Si2O5(OH)4 or Mg3Si2O5(OH)4 - (Fe2+, Fe3+)3-2Si2O5(OH)4, examining the impact of nickel and iron on chrysotile's properties. This study provides a review of the reported synthesis methods for chrysotile, emphasizing the synthesis techniques, precursor materials, and the resulting crystal chemistry. The findings highlight the dynamic nature of chrysotile synthesis research, with implications for materials science, including the development of novel nanostructures and environmental remediation technologies.