Scientists investigating the mysterious ‘alien glass’ in northern Africa have uncovered new clues about the violent event that created it.
The strange yellow material, known as Libyan Desert Glass, is scattered across parts of Egypt and Libya and is believed to have formed during an extreme cosmic event around 29 million years ago.
Now, researchers have discovered a rare zircon structure hidden inside the glass that appears to have formed after the mineral completely melted and rapidly crystallized again.
The finding suggests the glass was exposed to temperatures exceeding 4,082°F, hot enough to liquefy one of Earth’s most durable minerals.
Researchers believe the crystal preserved a microscopic record of that event, capturing evidence of the extreme heat and rapid cooling that created the glass.
But scientists still cannot agree on exactly what happened. Some believe an asteroid slammed into Earth, while others argue a space rock exploded in the atmosphere with enough force to melt the desert below.
The newly discovered crystal does not settle the debate, but it provides some of the strongest evidence yet that the event involved extraordinary temperatures and formed under highly chaotic conditions.
That finding is shedding new light on the origin of the mysterious glass that ancient Egyptians later prized enough to place in King Tutankhamun’s tomb.
Scientists investigating the mysterious ‘alien glass’ in northern Africa have uncovered new clues about the violent event that created it
That finding is shedding new light on the origin of the mysterious glass that ancient Egyptians later prized enough to place in King Tutankhamun’s tomb
Among the many treasures found in King Tut’s tomb were elaborate pieces of gold jewelry fashioned with pieces of the yellow glass.
Despite decades of study, researchers have never been able to fully explain how the glass was created.
However, the leading theories involve a catastrophic cosmic event.
One possibility is that an asteroid or comet struck Earth, generating enormous temperatures and pressures that melted silica-rich rocks into glass.
Another theory suggests that an incoming space object exploded in the atmosphere before impact, releasing enough energy to superheat the desert below without leaving behind a crater.
The biggest problem for researchers is that no definitive impact crater has ever been linked to the glass field.
Several candidate craters have been proposed over the years, but none have survived scientific scrutiny. That absence has fueled the ongoing debate and turned Libyan Desert Glass into one of planetary science’s most enduring mysteries.
In the latest study, researchers from the University of Milano-Bicocca in Milan, Italy examined a tiny zircon inclusion hidden within a sample of the glass.
The glass has been found in ancient jewellery, including a scarab carved from the material, which features in pectoral jewellery buried beside Tutankhamun
Zircon is an exceptionally durable mineral often used by geologists to reconstruct ancient events because it can survive conditions that destroy many other minerals.
What they found was unlike anything previously reported in Libyan Desert Glass.
The microscopic zircon measured only about 20 micrometers across, smaller than the width of a human hair, but it displayed an unusual branching, tree-like structure known as a dendritic texture.
Scientists believe the formation grew extremely rapidly from molten material as the glass cooled.
To investigate, the team used advanced imaging techniques capable of examining structures at the nanoscale.
These included electron microscopy and three-dimensional diffraction methods that allowed them to study the crystal’s internal structure in remarkable detail.
Chemical tests revealed that the trapped glass between the zircon branches was slightly different from the surrounding Libyan Desert Glass.
It contained higher levels of aluminum and zirconium, indicating it likely came from a separate molten droplet that cooled and solidified independently from the rest of the glass.
The researchers also found something unexpected: there was no evidence of minerals that normally appear when zircon melts and cools. Instead, every crystal they examined remained zircon.
That finding is shedding new light on the origin of the mysterious glass that ancient Egyptians later prized enough to place in King Tutankhamun’s tomb
This suggested the original zircon grain was heated so intensely that it melted completely before rapidly crystallizing again, skipping several intermediate stages that scientists would normally expect to see.
Further analysis showed subtle differences in the atomic structure of the trapped glass compared with the surrounding material.
The bonds between atoms inside the trapped glass were slightly longer, indicating it experienced a different thermal history during cooling.
According to the researchers, this supported the idea that the zircon formed from a tiny droplet of molten material that became isolated within the larger mass of molten glass.
The findings suggested the zircon crystal is a microscopic record of an extremely violent event.
Scientists believe it was created when intense heat melted both zircon and the surrounding silica-rich material, forming a droplet of liquid that cooled so quickly it froze evidence of the process in place.
However, the team noted that the finding carries an important implication.
Based on the chemistry of the zircon and surrounding glass, the team calculated that temperatures likely exceeded roughly 4,082 degrees Fahrenheit.
For comparison, lava from most volcanic eruptions reaches temperatures of about 1,292°F to 2,192°F, meaning the event that created the glass was significantly hotter than many volcanic processes.
The researchers described the conditions as being far from equilibrium, meaning the material was heated and cooled so rapidly that normal geological processes could not keep up.
They noted that the crystal’s unusual structure suggested it formed during a chaotic sequence of melting and rapid solidification, preserving evidence of the extreme conditions that created the glass.
The study also uncovered subtle differences between the glass trapped inside the zircon structure and the surrounding Libyan Desert Glass.
These differences indicate the material may have existed as a separate molten droplet before becoming trapped and preserved during cooling.
Although the discovery provides some of the strongest evidence yet for extreme heating, it does not settle the long-running debate over the glass’s origin.
