Iron-rich volcanoes may hold vast rare earth reserves, study finds

Currently, China dominates the global market for rare earths, accounting for 70% of mine output and 89% of refining.

Volcanoes with iron-rich magmas may hold significant concentrations of rare earth elements (REEs), according to a study published in Geochemical Perspectives Letters.

As reported by Eos magazine, laboratory experiments have shown that volcanic pressures and temperatures cause iron oxide-apatite (IOA) deposits to form, splitting magmas into two immiscible melts, one of which is highly enriched in REEs — up to 200 times more concentrated than in the silicate-rich melts.

Shengchao Yan, a doctoral student at the Chinese Academy of Sciences and lead researcher on the study, explained that when magmatic mixtures are subjected to volcanic conditions, they separate into two distinct components: an iron phosphate (FeP) melt and a silicate melt. This process results in REEs becoming concentrated in the IOA deposits.

The global demand for REEs, which are essential for green energy technologies, has surged in recent years.

Despite being relatively abundant, these elements are often difficult to mine due to their tendency to occur in small concentrations or in complex mixtures with other minerals. Unexpected discoveries of REE-enriched rocks have been made in iron mines in places like Sweden and Chile, located on extinct iron-rich volcanoes with large IOA deposits.

Michael Anenburg, an experimental petrologist at Australian National University and coauthor of the study, noted that the presence of rare earth elements is often overlooked in such mines.

“In many cases, we find REEs or other metals by accident,” he said. While these mines primarily extract iron oxide, further investigation may reveal untapped REE reserves.

Currently, China dominates the global market for rare earths, accounting for 70% of mine output and 89% of refining.