Fundamental university science is driving the discovery process for rare earth elements

September 05, 2022

Critical minerals are essential for tech we use today and for the green economy. Accessing these elements is thanks to innovation in Earth science research.

Image: The Australian Critical Minerals Research Centre is part of a drive towards sovereign capability in critical minerals. L-R: Diana Zivak, Fun Meeuws, Carl Spandler, Jarred Lloyd, Jess Walsh

Critical minerals are essential for tech we use today and for the green economy. Accessing these elements is thanks to innovation in Earth science research.

The critical minerals boom is driven by a transition to green energy and appetite for tech such as smartphones. Australia is well positioned to play a leading role in finding and extracting them. 

“For decades, university scientists have studied rare minerals in rocks to understand ancient geological processes,” explains John Mavrogenes, professor of economic geology at Australian National University (ANU). 

“Now these minerals are critical ingredients in the technologies we increasingly rely on in phones, batteries, electric vehicles, wind turbines and more. Looking forward, demand for critical minerals is only going to go up,” he says. 

The term ‘critical minerals’ is used to describe naturally occurring elements that are essential for modern technologies, economies and national security, and for which supply-chain vulnerability exists. Well-known examples include silicon (used in solar panels), lithium (for batteries) and cobalt (used in magnets). Geoscience Australia (GA) lists 45 minerals as critical in the Australian context, including 15 metals called the Rare Earth Elements (REEs).

Despite their name, REEs are not actually that rare in the Earth’s crust. However, to date they have been relatively hard to access, as they don’t typically occur in deposits rich enough to support traditional mining approaches. 

Better understanding of REE deposits – such as how they formed and why they occur in particular locations – will improve commercial opportunities and ensure reliable sovereign sources. 

Acheiving this requires a complex interplay between university science  and mining.

“The best exploration companies think very much like geologists at universities, and they fund people within universities to work on certain problems,” Mavrogenes explains. But the exchange goes beyond a ‘pay and find’ mentality. Fundamental university science is driving a discovery process that will completely change the way we search for these critical minerals into the future.

World-leading isotope science 

University of California, Los Angeles’ (UCLA) Distinguished Professor Mark Harrison is renowned worldwide for his expertise in isotope geochemistry. He undertook his PhD at ANU in the late 1970s and was director at ANU’s Research School of Earth Sciences from 2001–06. 

“In the 1960s–80s, ANU was the global leader in isotope science — that’s where the methods were being developed most aggressively,” Harrison says. “Now, those techniques university scientists started more than 40 years ago have absolutely blossomed into the capabilities for critical minerals exploration we have in universities and geological industries today.” 

A lab technique known as mass spectrometry is particularly vital for critical minerals research. It can identify forms of elements known as isotopes, which have subtly distinct masses due to differing numbers of neutrons. 

Measuring the relative abundance of isotopes gives scientists clues about how minerals formed millions of years ago.

“At ANU in the 1970s, we developed a mineral dating technique based on measuring two isotopes of argon, which is still widely used across the globe,” Harrison says. 

In the early days, spectrometry was used to date the geological evolution of the Earth. The world-first SHRIMP (Sensitive High-Resolution Ion Micro Probe) for spectrometry was created at ANU, revolutionising dating of minerals by removing the need for scientists to chemically process rocks and minerals before analysis. 

“SHRIMP offered a way around all the tedious chemistry we’d had to do up to that point,” says Harrison.

SHRIMP and more advanced isotope and dating technologies soon became established at other universities, but remained largely the domain of academia due to the persistence of some lengthy procedures and reliance on separate techniques for different elements. 

Analysing a whole mineral at once

In recent years, however, isotope science has become more commercially viable, thanks to important improvements in mass spectrometry.

A common approach is laser ablation ICP-MS (Inductively Coupled Plasma Mass Spectrometry), in which samples are scraped off with a laser; the resulting individual elements are converted into ions (charged particles) and then analysed in one step.

“This lets us perform accurate isotope analyses from one sample in just a couple of minutes, fundamentally changing the way minerals exploration can be done,” says Associate Professor 

Carl Spandler, director of the Australian Critical Minerals Research Centre (ACMRC) at the University of Adelaide. ACMRC was formed in 2021 to build expertise and knowledge around discovery of critical minerals. 

It’s part of a larger movement building critical minerals capacity in Australia. The government’s 2020 Modern Manufacturing Strategy includes critical minerals processing as one of its national manufacturing priorities. 

“Critical mineral discovery, separation and extraction – all of this requires the right techniques and an educated workforce,” Mavrogenes says. “There’s really important research still to be done on the rocks that carry critical minerals  in Australia.”

Mineralisation of REEs

ACMRC postdoctoral researcher  Dr Jessica Walsh is studying REEs in an ARC Linkage Project. Working with ANU scientists, state geological surveys, GA and Northern Minerals Ltd, Walsh aims to understand how mineralisation of REEs takes place, focusing primarily on geological formations in the Northern Territory and Western Australia. 

ARC Linkage Projects are designed to bring skills, knowledge and ideas from the university sector across to industry. Walsh brings mineral samples to the University of Adelaide labs and applies laser ablation ICP-MS to quantify REEs and measure isotopes of uranium and lead, so she can assess the age of the formations. “It’s incredibly fast – you can get a phenomenal amount of geochemical data really quickly,” she says. Exploration companies will use the data to help them understand the geology of their exploration sites, and to better target prospective areas to drill test for ore discoveries. 

Writer: Sarah Keenihan

First published in Australian University Science

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