Researchers at the University of Cambridge have created a groundbreaking global map pinpointing locations of rare earth element deposits, essential for technologies like smartphones and electric vehicles. This map emerged from an analysis of volcanic rocks and seismic data, revealing that these deposits are closely associated with the oldest and thickest regions of Earth's lithosphere. The study, published in *Nature Geoscience*, indicates that the thick lithosphere plays a crucial role in the formation of metal-rich igneous rocks. Lead author Dr. Emilie Bowman noted that their research provides predictive insights into where these valuable resources may be found, which is increasingly important as countries seek to secure domestic supplies amid rising demand. The researchers combined data from around 9,000 rock samples with seismic imaging to understand the geological processes that lead to rare earth concentration. The findings suggest that the conditions in the lithosphere limit melting and facilitate the gradual formation of economically viable deposits over time. The team plans to extend their research to include older geological formations, potentially uncovering further rare earth resources.