Pressure‐Induced Successive Phase Transitions and Optical Properties in Lu₂SiO₅

Herein, lutecium silicate is used as a rock example to investigate its two high‐pressure phases (7.4 GPa: HP‐II and 25.3 GPa: HP‐III) and lattice dynamics by in situ high‐pressure Raman scattering up to 35.1 GPa. The evidence for a highly symmetrical insulator HP‐III phase is obtained. Importantly, the high‐pressure structure (metastable phases) after pressure quenching is also intercepted, indicating pressure‐induced permanent densification. These findings provide Raman evidence for pressure‐induced successive phase transitions of highly symmetric insulators intercepted in prototype Lu 2 SiO 5 and physical insights to explain the self‐regulation of rare earth‐rich regions in facilitating highly effective global carbon cycling.