Glass strewn across southern Australia has been revealed to be the remnants of a previously unknown asteroid impact which happened about 11 million years ago (mya).

The search is now on to find the impact crater, which researchers believe could lie undiscovered in volcanic arcs surrounding Australia.

“These glasses are unique to Australia and have recorded an ancient impact event we did not even know about,” says Professor Fred Jourdan, geochronologist and geochemist at Curtin University.

“They formed when an asteroid slammed into Earth, melting surface rock and scattering debris for thousands of kilometres. These tiny pieces of glass are like little time capsules from deep in our planet’s history.”

The specimens analysed in the new study in Earth and Planetary Science Letters are ‘tektites’. The subtype of impact-produced glass is found in large ‘strewn fields’ located long distances from the impact crater which produced them.

(a) The 6 tektites analysed in the study, with the location they were found and mass. (b) Polished sections of the same samples under the optical microscope. Scale bars 2mm. Credit: Musolino et al 2025, Earth and Planetary Science Letters (CC BY 4.0)

Before now, there were 5 known tektite strewn fields around the globe:

• North American ‘bediasites-georgiaites’ which formed about 35 mya.
• Central European ‘moldavites’ which formed about 14 mya.
• Ivory Coast ‘ivorites’ which formed about 1 mya.
• Central American ‘belizites’ which formed about 800,000 years ago.
• And ‘australites’ which formed about 780,000 years ago and are spread over a large area from China to Australia.

New analysis of a subset of 6 pieces australites from the South Australian Museum’s collection has now revealed they were formed by a new impact altogether.

Lead author Anna Musolino, a PhD student at France’s Aix-Marseille University, says the glasses were distinct from all other known tektites.

“These tektites are unique because of their unusual chemistry and their age, which is about 11 million years,” she says.

“They record a completely separate impact event from the famous Australasian tektite-strewn field.

“While the Australasian tektites formed about 780,000 years ago and are spread across half the globe, these tektites are much older and their discovery suggests a previously unrecognised giant impact.”

(a) Trace element and (b) rare Earth element patterns for ananguites compared to Australasites. Credit: Musolino et al 2025, Earth and Planetary Science Letters (CC BY 4.0)

The researchers propose the name ‘ananguite’ for the new tektite strewn field, which spans across about 900km mainly within South Australia. They suspect that more ananguites remain to be identified among existing australite collections.

“What makes the discovery even more intriguing is that, although the impact must have been immense, scientists are yet to locate the crater,” says Jourdan.

The researchers suggest the isotopic and trace element analysis points to 3 possible sources associated with active volcanic arcs: Luzon (Philippines), Sulawesi (Indonesia), and the Bismarck region (Papua New Guinea).

Sulawesi, Luzon, and Bismarck arcs are the only ones showing compositions similar to those of ananguites. Credit: Musolino et al 2025, Earth and Planetary Science Letters (CC BY 4.0)

“Understanding when and how often large asteroids have struck Earth also helps us assess the risk of future impacts, which is important for planetary defence,” adds Jourdan,