Key points
- Spodumene is Australia’s key source of lithium.
- It is found inside hard rock pegmatite ores.
- We are working on ways to discover more deposits using hyperspectral technologies.
Take a moment to look around you. From mobile phones and laptops to cars, headphones, and cameras, rechargeable batteries power many of the devices we rely on every day. The beating heart of most of them is lithium-ion. In fact, the development of the lithium-ion battery led to the award of the 2019 Nobel Prize in Chemistry, from work that started in the 1970s.
Since the first lithium-ion battery was released in 1985, they have become synonymous with modern life. But where do they come from?
Australia’s lithium powerhouse: the story of spodumene
Well, if you’re in Australia, chances are the answer is spodumene – a pyroxene mineral composed of lithium aluminium inosilicate, with the chemical formula LiAl(SiO3)2. Australia is the world’s biggest producer of spodumene – around 47 per cent, and around 400 kilotons are mined each year.
Research Scientist Dr Jo Miles said spodumene is usually found in a type of igneous rock called pegmatite that forms when lava or magma cools.
“Pegmatites are coarse-grained and often form in the latter stages of a magma crystallising. Spodumene is the lithium-bearing mineral found inside the pegmatite,” Jo said.
The name “spodumene” is derived from the Greek word “spodumenos,” meaning “burnt to ashes.” That’s in reference to the ashy appearance of the mineral when it’s exposed to elevated temperatures.
For Jo and her colleagues in the Discovery Program, the challenge is discovering more spodumene deposits, because demand for lithium is only growing.
Seeing what your eyes can’t see
The race is on globally to find more deposits of critical minerals such as lithium.
Jo said that we work with a vast range of minerals. Unfortunately, not all pegmatites contain spodumene, which makes it hard to find. Additionally, no spodumene is the same as another, thanks to factors such as weathering.
“When looking at the reflectance of minerals and spectroscopy, minerals absorb light at different wavelengths across the electromagnetic spectrum,” she said in reference to the chart above.
“However, most technology focuses on the visible and near-infrared (VNIR) and short-wave infrared (SWIR) which only gives us a small piece of the puzzle,” she said. Other wavelengths include mid-infrared (MIR) and thermal infrared (TIR).
The quality and quantity of deposits also wildly varies. Pegmatites differ in size, some only a few meters in size. These are beyond the detection capabilities of some technologies such as satellite imagery. Meanwhile, others are much larger, but may not be at the surface, and therefore beyond the range of current remote surface detection.
Therefore, we are working on several ways to improve how we detect minerals such as spodumene.
Developing new ways to find pegmatites
Jo’s own work utilises a multi-method approach to advance the science of mineral systems to aid discovery.
“I currently focus on hyperspectral technologies – including satellites – that sense the chemical composition of surface minerals at a range of scales and resolutions,” Jo said.
“In terms of my spectral work, I like combining my understanding of the short-wave infrared. We observe a pegmatite’s alteration such as white mica, and the thermal infrared to detect the lithium ore directly, such as the spodumene.”
However, her research is just part of our Discovery Program within Mineral Resources. The wider program has several different focus areas.
For instance, some are advancing mineral exploration strategies by using microscopic-scale analysis of pegmatites. It provides deeper insights into the thermodynamic conditions governing the formation of different oxides.
Others are using machine learning to help find lithium pegmatites in the Pilbara using our Landscape+ framework.
Meanwhile, different teams are advancing our understanding of where lithium-bearing igneous rocks, such as pegmatites, are found. By comparing the various footprints of these rocks across Australia, they are learning how variable they are to better target prospective deposits.
Together we’re working with industry to overcome their challenges, and make sure that the world’s lithium needs are met.