Strange glassy blobs strewn across the Australian desert are evidence of an ancient meteorite impact that scientists hadn't noticed until now.

According to a new analysis led by geoscientist Anna Musolino of Aix-Marseille University in France, tiny spheres of glass found in South Australia represent an impact-melt composition not found anywhere else in the world.

These newly named ananguites, the researchers say, formed in a giant impact that took place some 11 million years ago.

The sting in this particular tail is that geologists have yet to find any trace of a crater associated with this event – an event powerful enough to leave mineral traces that persist in detectable quantities for millions of years.

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

"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.

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

The desert across southern Australia is positively strewn with tiny beads of impact glass called tektites. It's part of a region known as the Australasian strewnfield, the fallout created by a giant meteorite impact thought to have hit somewhere in Southeast Asia around 788,000 years ago.

The tektites from this fallout found in Australia are known as australites, and they're particularly abundant partly because the suspected impact took place a relatively short time ago.

Way back in 1969, scientists Dean Chapman and Leroy Scheiber of NASA made a chemical analysis of 530 australites. Among that number, they found eight with a mineral composition that did not match the rest of the sample.

They noted the strangeness of this, suggesting the eight beads may have formed in a separate impact, but no one ever really followed up.

Musolino and her colleagues decided to dive back into the oddballs to figure out what their deal is. The original eight samples were unavailable for re-analysis, but luckily Chapman and Scheiber had provided a detailed chemical description of the oddballs.

The differences of particular note include lower silicon dioxide content, but higher levels of the oxides of iron, magnesium, and calcium. They're also denser, with higher magnetic susceptibility, different bubble patterns, and different ratios of trace elements.

The six newly discovered ananguites. (Musolino et al., Earth Planet. Sci. Lett., 2025)

With this profile in hand, the researchers scoured the australite collection at the South Australian Museum, screening it for outliers consistent with the oddballs identified by Chapman and Scheiber. They found six new tektites in the collection that matched the mineral fingerprint of the earlier anomalies.

The composition of these ananguites strongly indicates that they formed in an impact that occurred on a different part of the crust from the Australasian strewnfield impact.

To confirm, Musolino and her colleagues performed argon dating on two of the six samples; Jourdan and other researchers had used the same technique in 2019 to date tektites scattered around Southeast Asia and Australia to 788,000 years old.

The team deduced that the newly identified ananguites are 11 million years old – significantly older than the tektites. This age clinches it; this handful of tiny glass blobs formed in a different, earlier impact.

Where that impact took place, however, is still a big mystery. That's not surprising given the source crater of the Australasian strewnfield tektites is still unknown, considered something of a "holy grail" for impact cratering science.

There are also a few reasons why the ananguite source crater might have vanished, including intense weathering and the aridification of central Australia that started around 33 million years ago. It may also have been mistaken for a volcanic feature in regions such as Papua New Guinea.

"Geochemical and petrographic systematic differences between western and eastern ananguites, which still need to be confirmed with additional samples, may help constrain the location of the impact," the researchers write in their paper.

"However, it is also possible that the crater has been buried during the past 11 million years."

The findings have been published in Earth & Planetary Science Letters.