Extinct volcanoes yield new sources of rare-earth metals: Study

Researchers from the Australian National University (ANU) and the Chinese Academy of Sciences have announced groundbreaking findings on extracting rare-earth elements from the interiors of extinct volcanoes. This discovery could significantly impact global supplies of these valuable resources, which have applications in many industries.

Rare-earth metals, also known as rare-earth elements (REE), are a group of 17 chemical elements. They are challenging to extract due to their strong dispersion and small deposits, and they never occur in pure form. Their total content in the Earth's crust is 164 ppm, which is relatively small compared to other elements, such as oxygen, which has a content of 464,000 ppm, or gold, which occurs in amounts of about 0.004 ppm.

Rare-earth metals are less profitable to extract than gold, yet demand for them continues to rise steadily. This is due to their wide range of applications in different sectors of the economy. They are used in the production of smartphones, digital camera lenses, wind turbines, computer hard drives, batteries, LED lights, lasers, electric car motors, monitors, and televisions. China is responsible for about 70% of the total global production of rare-earth metals.

The latest research conducted by ANU and the Chinese Academy of Sciences shows that the interiors of extinct volcanoes can be a valuable source of rare-earth metals. A paper published in the journal "Geochemical Perspectives Letters" reveals that magmatic rocks from inactive volcanoes contain significantly higher amounts of REE than rocks from active volcanoes.

Dr. Michael Anenburg, a geologist from ANU and a co-author of the study, stated, "We have never seen an iron-rich magma erupt from an active volcano, but we know some extinct volcanoes, which are millions of years old, had this enigmatic type of eruption." Dr. Anenburg also added that such volcanic deposits could be found worldwide.

Scientists conducted several experiments at the ANU Experimental Petrology Laboratory to understand the impact of the conditions under which iron-rich magma forms on the REE content. They obtained rocks similar to those from iron-rich extinct volcanoes by simulating volcanic eruptions.

Chemical mixtures with compositions corresponding to volcanic rocks were placed in a pressure furnace and heated to between 800 and 1500 degrees Celsius (1470–2730 degrees Fahrenheit) for two to five days until they were completely melted. After analyzing these rocks' chemical and mineralogical composition, scientists found that the highest concentration of REE is located in phosphate group minerals, such as apatite, monazite, and xenotime.

The research results were surprising. The laboratory-produced rocks contained up to 100 times more rare-earth elements than some currently exploited deposits. Currently, the largest global deposits of rare-earth metals are in China, while in Europe, their potentate is Sweden. However, according to Dr. Anenburg, Australia could soon become a significant player in the REE market thanks to the exploitation of new deposits.