Cosmos
Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.
By Cosmos
As the world transitions to more sustainable technologies, there is a growing need to find the metals that help make those technologies.
Critical minerals, such as rare earth elements (REE)are vital for numerous high-tech applications, including electronics, magnets and batteries. Lithium (Li), another critical mineral, is lightweight and energy dense. This makes it ideal for rechargeable batteries.
Dr Naina Goswami is a Research Projects Officer at CSIRO’s infrared spectroscopy team who works across different research platforms looking at lithium and REE-hosting minerals.
Goswami focuses on expanding knowledge of these important minerals and elements, to develop more efficient and streamlined critical metal discovery practices.
She is currently studying the fluorophosphate mineral amblygonite, an important source of lithium, phosphorous and fluorine.
“We can find amblygonite in pegmatites which are coarse igneous rocks. Studying it will strengthen our understanding of lithium mineral systems and help us identify phases of lithium deportment – the way it moves within the pegmatites,” Goswami says.
“Importantly, knowing the distribution and chemistry of amblygonite is crucial to improving lithium extraction processes.”
“At first glance,” Goswami says, “…it can sometimes be mistaken for albite or other minerals from the feldspar group due to its white colour.
“Even though it’s a bit too soft, it’s sometimes used as a gemstone, when it can be found in some of its other pretty colours. These include blue, green, yellow and pink and even lilac.”
Amblygonite however is mostly used to help us understand ore-forming systems and geological settings and has been identified by CSIRO as a mineral of interest.
“With some of my colleagues, I’m investigating the crystal structure, composition, and spectral features of amblygonite.
“The results will improve our understanding of the chemistry of amblygonite and why there are changes in abundance of amblygonite in different geological settings.”
Another mineral being studied at CSIRO is monazite which can exhibit different colours in rocks, including red, brown and green. This phosphate mineral is also notably hard.
It can be found in a variety of natural settings, including beaches, and riverbanks. Monazite is in magmatic rocks (cooled and hardened molten rock), metamorphic rocks (rocks transformed under intense heat and pressure), or rocks cooked with high temperature fluids.
CSIRO Senior Research Scientist, Dr Siyu Hu, says monazite is an important REE host.
“Studying monazite helps me understand how REE move within the deposits and provide insight into the geological processes that form these deposits,” Hu says.
“Knowing monazite and other REE-bearing minerals distribution within these deposits, particularly during exploration, is critical for extracting them efficiently.”
What are rare earth elements, and why are they important?
REE include 15 of the lanthanide series of elements, in addition to scandium and yttrium. Neodymium-based magnets (also called superior magnets) with added dysprosium, another rare earth, are a crucial component of electric vehicle motors and wind turbines. REE are also used as phosphors (a luminescent substance), allowing us to see the colours in TV screens and computer monitors.
Despite the name, REE are not necessarily that rare. For example, cerium (Ce) is as plentiful as copper in the Earth’s crust. However, REE typically occur in such relatively low concentrations that commercial mining operations often struggle to make them economically viable.
Techniques to study minerals such as amblygonite and monazite include X-ray diffraction, Scanning Electron Microscopy and Fourier-Transform Infrared Spectroscopy. The data collected by CSIRO researchers contributes to spectral libraries and is used in mineral exploration.
The Australian and international geoscience community is using reflectance spectral signatures of reference mineral samples to efficiently and objectively identify and characterise mineral groups and species by means of these proximal and remote spectral sensing technologies.
Applications range from regional mineral exploration using spaceborne technologies to identifying deleterious minerals encountered in ore processing plants and soil classification for land use management.
Publicly available spectral reference libraries (SRL) of rock-forming minerals are crucial for the processing of the voluminous hyperspectral data sets. The CSIRO-led National Virtual Core Library project (NVCL), has initiated this internet accessible collection of reflectance spectral signatures acquired from validated reference mineral samples.
While established technologies exist for identifying critical minerals in rock samples, identifying rich deposits on a larger scale, such as through satellite imagery, remains highly desirable but extremely challenging. Dr. Carsten Laukamp, CSIRO Principal Research Scientist, is leading a team dedicated to developing new hyperspectral approaches for the cost-effective characterization of such deposits using satellite remote sensing.
From two articles originally published in CSIRO News
One to watch: amblygonite helps us understand ore-forming systems
Meet monazite, a pathfinder to rare earth elements
