In their element: celebrating our scientists and their mineral namesakes

By  Ruth Dawkins 16 August 2024 6 min read

It’s been more than forty years since our researcher, Dr Dave Wadsley, was honoured with a new mineral in his name. Wadsleyite received its name in 1983, in recognition of Dave’s outstanding crystallographic investigations of minerals and inorganic compounds.

In the decades since, nine other CSIRO researchers have received the same recognition.

Our latest mineral namesake has been dubbed macraeite. It recently received approval after efforts driven by Dr Ian Grey, a CSIRO Honorary Fellow in the Microbeam and Diffraction Group, and Dr Nick Wilson, Team Leader in Electron Microscopy and Analysis.

Macraeite is named after Colin MacRae, a research scientist who directs microanalysis research in our microbeam and XRD (X-ray diffraction) laboratories.  

“I found out in quite a funny way because I was at a conference in Paris and got a bizarre text from Nick telling me to check my email. When I opened up my computer, there was a message from Ian asking if they could name the mineral after me,” Colin says.

“Of course, I said yes. It really is such an honour to have a mineral named after you.”

It's quite a process to characterise and name a mineral

“For something to be considered a mineral, it has to be naturally occurring. Not a manufactured material,” Nick says.

“It also has to be non-biological and generally it has to be crystalline. To be considered a new mineral, it must have a different crystal structure or chemistry from existing minerals.”

In the early 20th century, new minerals were discovered at a rate of around 10 per year. Due to continuing improvements in the technology used to analyse samples, the current rate of discovery is more like 120 per year.

“The major work of defining a new mineral is determining its crystal structure, which is done using X-ray diffraction techniques,” Nick says.

“There are lab-based machines that can do it, although Ian quite often collects diffraction patterns at the Australian Synchrotron, which is operated by the Australian Nuclear Science and Technology Organisation (ANSTO).”

“From the diffraction patterns collected on the instruments, Ian can then work backwards to calculate what crystal structure generated them.”

Other key steps in characterising the mineral include working out the chemistry and measuring the optical and spectroscopic properties. Once that analysis is complete, the characteristics of the potential new mineral can be compared to known minerals.

If they are found to be significantly different, researchers submit a naming proposal to the International Mineralogical Association, which then votes to determine whether it should be accepted as a new mineral. 

Fifty years of mineralogical research and more than 60 new minerals

Lead author for the macraeite naming proposal, Ian first joined what was then called CSIRO Mineral Chemistry in 1970.

For more than 50 years Ian has worked closely to characterise and name over 60 new minerals. Notably, Ian has achieved the even rarer feat of defining several mineral groups. Typically, only four new mineral groups are defined each year. 

For his achievements in his field, Ian has also been acknowledged with his own mineral namesake. A phosphate mineral from Silver Coin Mine in Nevada has been called iangreyite.

“It’s very nice to achieve mineralogical immortality,” Ian says.

“Although it’s important to note that the person who the mineral is named after must not be involved in the naming process.”

This rule means that although Colin MacRae did much of the microanalysis on the mineral that now carries his name, he is not included as an author on the paper itself. However, he believes it would have been impossible to find a better person to steer macraeite through the characterisation and naming process. 

“Ian is hugely respected internationally,” Colin says.

“My hat goes off to him. It’s quite astounding how renowned he is.”

Even though he’s now retired from a full-time role with CSIRO and only comes in one day a week, Ian is still describing around five minerals a year. 

Ongoing innovations in mineralogy research

According to Ian, the work of characterising and naming new minerals is a collaborative international effort, starting with the collectors themselves.

“We are dependent on enthusiastic collectors and mineralogists to locate potential new minerals on their field trips,” Ian says.

“They provide specimens for us to characterise.”

When it comes to the analysis of those specimens, a lot of work takes place at our cutting-edge research facilities. However, Ian and Nick’s co-authors on the macraeite paper are based at research institutions in Germany and the US.

What united them was a recognition of the research breakthroughs that Colin has achieved in developing novel electron microprobe techniques.

“The tricky thing with the suite of new minerals we’ve worked on from the paulkerrite group, of which macraeite is a member, is that they are highly hydrated,” Colin says.

“They contain at least 30 per cent water. High amounts of water are normally incompatible with the electron microprobe analyser (EPMA) because the water starts to evaporate when the sample is placed in a vacuum, and it messes up the analysis.”

To overcome this challenge, Colin has developed a process to cryogenically freeze the samples when they are placed in the sample holder.

Using cryogenically cooled liquid nitrogen gas, the temperature comes down to around -194°C. This slows down the loss of water and keeps the sample more stable during microanalysis.

“That work we’ve done using cryogenic methods, along with Nick’s work developing new quantitative analysis software, is all brand new really. It’s made it possible for us to solve these mineral chemistries correctly to the point where in some cases we are actually redefining it,” Colin says.

One of the reasons why that’s really useful is that if you’re working on a new resource, say a rare earth deposit, that knowledge about the structure of the mineral helps you understand how to process it. It can tell us how to remove and recover it.

"A mining or a mineral processing company can take that fundamental knowledge and then apply it very quickly in the real world.”