The researchers ofAustralian National University (ANU) and theUniversity of Chinese Academy of Sciences have published a study in which they highlight how in correspondence with the extinct volcanoes large deposits of rare earths may be found. These metals would be found concentrated in the minerals that originated from the cooling of the iron-rich magma. The discovery, made thanks to laboratory simulations, is potentially very important as rare earths are critical raw materials indispensable for creating electronic and magnetic devices and those of plants for energy transition. The potential importance of this discovery is also of a geopolitical nature, because currently the largest exporter of rare earths is China, which consequently has a clear dominance on the market of these fundamental materials for the creation of electronic devices.
The study of extinct volcanoes
THE extinct volcanoes they are those that in historical times have not shown signs of activity, whose eruptions we have therefore never witnessed. “We have never seen iron-rich magma erupt from an active volcano“says Michael Anenburg, a geochemist at the Australian National University and author of the study. “But we know that some extinct volcanoes, which are millions of years old, have had this particular type of eruption“. The researchers managed to understand how rare earths can accumulate in the magma erupted anciently from these volcanoes using rocks rich in iron phosphates and silicates. The material was placed in pressurized ovens, with a pressure equivalent to that present at a depth of 15 km in the earth’s crust. The rocks were heated to a temperature of 1100 °Cuntil they melt. In this way, the iron-rich magma erupted by ancient volcanoes was reproduced and found to be able to concentrate rare earth metals almost 200 times more than “normal” magma.
The importance of the discovery of extinct volcanoes
The fact of having identified where deposits in which the rare earth content is concentrated can be found is fundamental. In fact, the main critical issue linked to the extraction of these metals is theirs low concentration in the rocks. They are called “rare earths” precisely because it is difficult to find them in high concentrations in a deposit (and not because they are uncommon) and consequently the extraction process is expensive and complex. Not all extinct volcanoes have iron-rich magma and therefore a high rare earth content. Those rich in iron, however, in light of this study, should be explored in more depth. Furthermore, confirmation also comes from the enormous rare earth deposit discovered in Kiruna, Sweden: here the precious metals were identified in high concentrations within volcanic rocks rich in iron oxides. Among the countries indicated as the site of possible deposits are Australia and Chile, where the El Laco volcano is located. Extinct volcanoes are often already exploited foriron extractionso their mines can also be used to obtain rare earths, without compromising the environment with the creation of new excavations.
The global implications
There demand for rare earths has increased significantly in recent years and is destined to grow. China understood the importance of these materials well before the West and now holds the lead in their extraction and processing, even if its market share has shrunk in the last decade. Identifying deposits in Western countries is therefore essential to reduce dependence on Beijing and also protect oneself in the event of export restrictions that China could apply in the event of any conflicts between states.
