A giant impact on the Earth’s surface could be a catastrophe with far-reaching effects. They can excavate huge craters such as: Vredefort Crater. There’s also growing evidence that a powerful enough shock could create giant cracks and chemical hydrothermal systems underground, which could lead to the birth of life.

These are the people who attract attention in the world of impact.

But there are many other lower-energy meteorite impacts that are more difficult to detect, and they are also important parts of Earth’s history. These impacts generate extreme heat that can melt rocks. When that happens, the impact can create a huge field tektitea pebble-sized chunk of natural glass. There are five of these tektite fields around the world, each telling a part of Earth’s story.

Brazilian researchers have discovered another tektite deposit, the first in the country.

The title of their study is “Gelasite: Tektite first produced in Brazil” was published in the journal “Geology”. The lead author is Alvaro Crosta, geologist and senior professor at the Institute of Geosciences of the State University of Campinas.

“We report the discovery of a new tektite-strewn field in northeastern Brazil,” the authors write. “This recent discovery has resulted in the collection of approximately 500 specimens found within a scattered field at least 90km long.” They name these pieces “gerasite” after the Brazilian state of Minas Gerais.

*Tektite fields were discovered in Minas Gerais, Brazil, and tektite was given the name “geraisite.” Image credit: Crosta et al. 2025. Geography*

Geraisite ranges in size from less than 1 g to 85.4 g and comes in a variety of shapes. This is typical of tektites, and so is their chemical composition.

*This photo shows part of the size and shape of tektite/geraisite. They tend to be round, but some are elongated. It is also black and has characteristic unevenness on its surface. Image credit: Crosta et al. 2025. Geography*

At the time the paper was written, this field was 90 km long, but subsequent efforts have discovered many more tektites in a larger area 900 km long. “This increase in the area of ​​occurrence is completely consistent with what has been observed in other tektite areas around the world. The size of the area directly depends on the energy of the impact, among other factors,” Klosta said. press release.

When researchers study these rocks, they need to distinguish between rocks of volcanic origin and tektites. It’s not easy. Both types of rock are exposed to heat and can spread over large areas.

Tektites have several things in common that help scientists identify them. They are fairly homogeneous, have extremely low moisture and volatile contents, and have no chemical relationship to the local rock formations in which they are found.

Water content is an important part of differentiating volcanic rocks from tektites. “One of the decisive criteria for classifying this material as a tektite was its very low water content, measured by infrared spectroscopy, between 71 and 107 ppm. For comparison, volcanic glasses such as obsidian typically contain between 700 ppm and 2% water, whereas tektites are notoriously very dry,” Klosta said.

Tektites may contain many Le Chatelierite. Lechatelierite is a silica glass formed from quartz by high-pressure shock metamorphism. They are also often seen near lightning strikes. Lectites distinguish tektites from volcanic rocks that may or may not contain lechatelierite, since the magma may have originated deep in the silica-poor mantle.

Compared to some tektites, gelaisite has very few inclusions of these lechatelierites. Obsidian, a volcanic glass, usually does not contain lechatelierite, which helps rule out the possibility of volcanic activity. There is no other evidence of volcanic activity nearby. “Confirmation that this glass occurrence is composed of tektites makes sense given that the geographic location in which it was discovered is not volcanic, and the closest known volcano of similar age is in the Andes Mountains, more than 2,500 km away,” the authors write.

*Further investigation revealed that the length of the tektite field is approximately 900 km. Image credit: Crosta et al. 2025. Geography*

There are also no craters, which seems to contradict the tektite interpretation. “The potential source craters associated with this tektite-strewn area are not yet known in Brazil or in neighboring countries,” the researchers explain. But researchers say it’s not uncommon. There are six large tektite zones on Earth, but only three of them have specific craters associated with them.

The researchers used the argon isotope ratio (⁴⁰Ar/³⁹Ar) to date the germaisite. “The best estimate of their age of formation is ⁴⁰ah/³⁹The Ar method is currently about 100 seconds. 6.3Ma, but there may be a genetic disease ⁴⁰“Further analysis will be required to fully determine the age of Ar,” the authors wrote in their paper.

The size of the impact object cannot be determined at this time, but researchers say it is unlikely to be small.

“The discovery of the first tektite-strewn areas in Brazil, together with a potential link to an as-yet-undiscovered impact event 6.3 million years ago, fills a major gap in the incomplete South American impact record,” the authors write in their conclusion.

This record is incomplete in South America because craters are difficult to spot from the air, but this is mainly due to the high rate of crater removal due to tropical weathering. Craters can be preserved much longer in dry desert locations than in South America. Also, this continent has not been as geologically explored as other continents.

However, the tektite content imposes some constraints on where craters may exist. Isotopic geochemistry shows that the tektites came from continental crust about 3 billion years ago. it suggests that it came from san francisco craton. The craton is an ancient part of the Earth’s continental crust and one of the oldest in South America.

“The isotopic signature points to a very old continental granitic source rock, which significantly reduces the extent of the candidate region,” Crosta said. Deeper exploration of the area could reveal the remains of an ancient crater.

*This image shows cratons in South America and Africa that are more than 1.3 billion years old, including the San Francisco Craton. Image credit: Written by Woudloper – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9857099*

The discovery of this tektite zone, and another recently discovered in Belize, suggests that they may not be as rare as thought. Discovering more of them could change our understanding of the Earth’s record of impacts.

“This has important implications for the global impact record and suggests the possibility of undiscovered tektites with distinct origins, chemical compositions, and ages,” the authors conclude.