Key points
- Microcline is a mineral found in pegmatite deposits together with critical minerals such as lithium.
- Under polarised light, potassium and sodium in microcline creates a tartan-like pattern.
- We are exploring new uses for unused mine materials as potential building blocks for space construction.
You may have seen the mineral microcline around the place before as a decorative stone. Often turquoise or white in colour, it can also appear pink, or cream. Like many minerals, tiny trace amounts of elements like chromium, iron, cobalt, nickel, etc, can alter a mineral’s colour.
Microcline is a type of feldspar mineral, which is a key component in granites and the Earth's crust. It forms during the slow cooling of certain rocks like pegmatites, which are known for containing valuable minerals like spodumene (a key source of lithium). You might be lucky to find it in New South Wales and Western Australia.
While currently used in ceramics and glassmaking, it is an important mineral component of many rocks.
However, according to our Senior Spatial Scientist Dr Romana Dew, its uses might eventually change.
“Microcline’s presence or absence in geopolymers tells us a lot about the reorganisation of the original rock components and the chemical reactions taking place,” Romana said.
“These geopolymers incorporate materials leftover from mines and could be applied to create materials on other planets!”
Wait a second – that’s quite a jump from fashionable knick-knacks to space building blocks. How would that work?
Space-saver for space missions
Though costs are steadily decreasing, it’s still very expensive to send material into space. If humans are to create bases – let alone colonies – on the moon or Mars, we cannot just send up thousands of tonnes of cinder blocks. Given that mining would most likely occur at off-planet facilities, what would happen with a common spoil from the waste rock?
Enter geopolymers. Geoploymers are ceramic-like materials often made using industrial byproducts to produce things like cement.
“Having the ability to create rocks or building blocks in space is highly advantageous and cost effective,” Romana said.
“As a result, we could transport a small amount of the reagents to create rocks in situ. We could use geopolymers with a bonding agent, similar to cement binding concrete.”
The result would be very advantageous use of mine by-products. Critical minerals could be extracted, and the waste turned to building materials.
“Within the Sustainable Mining Technologies Program at CSIRO, we have developed a set of methods similar to concrete construction, to create synthetic rocks or geopolymers,” Romana said.
Work is currently underway to utilise mine byproducts in new forms and finding earthly analogues of lunar and Martian landscapes to test and trial technologies before they go into space.
A tartan link that could span space and origins
Under the microscope, microcline is possibly even prettier. It usually shows a unique tartan or grid-like pattern on its surface – called "twinning" – when viewed under a microscope.
Romana said the twinning pattern is distinctive to microcline and is created from the relationship between potassium- and sodium-rich components during its formation.
This elemental relationship is important to create geopolymers for construction use on earth or in space. So, the presence or absence of microcline tells us a lot about the way the geopolymers bond.
Romana has always loved geology, and has had an amazonite variety of microcline as part of her rock and gemstone collection since childhood.
However, though she didn’t know it at the time, that tartan twinning that’s created during the mineral’s ancient past would have a link to her own origins.
“Recently, I completed a DNA ancestry test, revealing over 70 per cent Scottish Highlander and Irish background,” she said.
“Now, every time I examine the tartan-patterned microcline, I smile, feeling a deeper connection to my Celtic heritage!”