Key points
- Monazite is found in all sorts of places, including beaches, riverbanks, in magmatic rocks and metamorphic rocks.
- It's a significant source of rare earth elements, essential for powering today's advanced technologies.
- Our research delves deep into understanding monazite, including developing methods for dating it and analysing its chemical and spectral properties.
Marvellous monazite can exhibit different colours in rocks, including red, brown and green. This phosphate mineral is also notably hard.
You can find monazite 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.
Our Senior Research Scientist, Dr Siyu Hu, is currently focusing her research on the study of monazite. She says monazite is an important ore for rare earth elements (REE) and thorium.
"Studying monazite helps me understand how REE move within the deposits and provide insight into the processes that form these deposits," Siyu says.
"I’m particularly interested in the carbonatites which are enriched in magmatic carbonate minerals. These serve as the primary source of light REE to the world.
"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.
Despite the name, REE are not necessarily that rare. For example, cerium 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.
These elements are vital for numerous high-tech applications, including electronics, magnets and batteries, catalysts, ceramics and glass. Neodymium-based magnets (also called superior magnets) with added dysprosium, another rare earth, are a crucial component of electric vehicle motors and wind turbines.
Interestingly, REE are used as phosphors (a luminescent substance), allowing us to see the colours in TV screens and computer monitors.
As high-tech societies transition towards clean energy, the European Union (EU) forecasts REE demand increasing tenfold over the next 50 years.
Monazite geochemistry and developing work
Monazite contains varying amounts of REE, usually cerium, lanthanum, and neodymium.
It can also contain thorium, making monazite radioactive, requiring careful handling. Scientists use this radioactivity in monazite to determine the timing of geological events, including ore formation.
One of Siyu’s colleagues is working on a monazite dating method in-house, using our new and advanced laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).
Other work includes investigating the spectral features of monazite and other REE-bearing minerals.
"By building this fundamental knowledge, we aim to develop new approaches to help quickly identify REE-bearing minerals," Siyu says.
"We’ll use cutting-edge drill core sensing technologies, such as our CSIRO-developed HyLoggerTM, that has been commercialised with Australian METS Corescan Pty Ltd.
"Some of our other work includes investigating efficient methods for extraction of REE and thorium from monazite."
Large-scale identification of monazite-bearing deposits
To identify monazite in rock samples, we’ve established technologies such as optical microscopy, scanning electron microscopy, and X-ray diffraction.
“Identifying monazite-bearing deposits on a larger scale, such as from satellite images, would be game-changing, but extremely challenging,” Siyu says.
However, changing the game is what we do.
Siyu and her colleagues are researching new approaches for cost-effective use of thermal infrared satellite sensors for characterising REE deposits. This innovative approach could revolutionise the way we explore and manage rare earth resources in the future.