Termite mounds send clues on unknown deposits

The blue metallic shine of manganese crust incorporated into this termite mound in the southern Pilbara region of Western Australia contains zinc isotopes that can reveal the presence of hidden metal deposits nearby. Image: CSIRO

Metallic blue crusts within soil and termite mounds could be a signpost for hidden metal deposits in the southern Pilbara region of Western Australia.

A CSIRO study from the region shows how metallic blue crusts, known as manganese crusts, display unique zinc characteristics that indicate the presence of other base metals in the area.

These include nickel and cobalt, elements that are essential in the global transition towards a low emissions future.

The manganese crusts are also found in rock and cave varnishes, making them an easily accessible exploration tool for base metals.

“As the world transitions to a low emission future, there’s a need for more nickel and cobalt to build electric vehicles and batteries to store renewable energy,” CSIRO senior research geoscientist and lead scientist on the research, Sam Spinks said.

“We’ve shown that analysing zinc isotopes found in manganese crusts have huge potential to be used to explore for these metal deposits, and others.”

The CSIRO has proven the connection by comparing its analysis of termite mounds and soils located close to a zinc-lead-silver deposit to other samples.

Spinks said zinc was commonly found in most base metal deposits, and over time ended up in a range of natural materials including soils, termite mounds and vegetation.

“The zinc is altered as it moves from the metal deposit to the surface, which has traditionally made it unreliable as an exploration tool, but we’ve been able to apply recent advances in data analysis to understand it in more detail,” he said.

“This new research shows we can now measure zinc variations, or isotopes, so accurately that we can identify what metal deposit lies deep underground.”

Termite mounds are already being used in Australian exploration, following earlier CSIRO research that found termites extract small particles from ore deposits to store in their mounds.

“Australian exploration companies have been analysing samples from termite mounds in gold exploration in recent years, now zinc offers another technique for use in broader environments and to find a range of metals,” CSIRO research group leader Yulia Uvarova concluded.

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