Brazil Confirms Discovery of 6.3-Million-Year-Old Tektites Linked to Massive Meteorite Impact

The Brazilian scientific community has officially validated the discovery of tektites within its borders—rare fragments of natural glass created by a colossal meteorite impact approximately 6.3 million years ago. This landmark finding, detailed in the December 2025 issue of the journal Geology, places Brazil among an elite group of only seven regions worldwide where such cosmogenic events have been documented. The discovery marks a significant milestone for South American geology, providing tangible evidence of high-energy celestial collisions in the continent's distant past.

Unlike volcanic obsidian, tektites are characterized by an exceptionally low water content, typically comprising less than 0.03% of their total weight, which serves as a definitive marker of their extraterrestrial origin. Prior to this revelation, the scientific world recognized five primary tektite strewn fields: the Australasian, Central European, Ivory Coast, North American, and Belizean fields. The Brazilian research was spearheaded by Professor Alvaro Pinteado Crosta, a distinguished Senior Professor at the Institute of Geosciences at the University of Campinas (Unicamp). Professor Crosta, who has specialized in impact structures since the 1970s, collaborated with experts from the University of São Paulo (USP) and international research centers located in France, Austria, and Australia.

The newly discovered specimens have been named "Geraisites" in honor of the municipalities where they were found, including Tayobeiras, Curral de Dentro, and São João do Paraíso. Rigorous chemical, isotopic, and geochronological testing was conducted to confirm their identity, successfully ruling out volcanic origins by identifying lechatelierite—a high-temperature silica glass inclusion unique to impact events. To date, more than 600 individual fragments have been recovered across a vast area spanning over 900 kilometers. This extensive distribution field stretches across the Brazilian states of Minas Gerais, Bahia, and Piauí, suggesting an impact of immense proportions.

The physical characteristics of the Geraisites are diverse, with individual masses ranging from less than one gram to a significant 85.4 grams. Their shapes—spherical, ellipsoidal, teardrop, and dumbbell-like—reflect the aerodynamic forces they encountered while being ejected through the atmosphere in a molten state. Isotopic analysis involving strontium, neodymium, and hafnium suggests that the meteorite struck a continental, likely Mesoarchean, felsic crust. This data is crucial for reconstructing the paleogeography of South America, as it adds a vital new chapter to the continent’s geological record and helps scientists understand the environmental conditions of the late Miocene epoch.

Professor Crosta, renowned for developing the "Crosta Technique" for mineral exploration via remote sensing, has dedicated decades to mapping Brazil's impact structures. As of 2026, the primary objective for the research team is to locate and precisely map the massive impact crater that corresponds with the age and target rock type of the Geraisites. The 900-kilometer spread of the samples aligns with patterns observed in other global tektite fields, where the size of the strewn field is directly proportional to the energy of the initial collision. Derived from the Greek word tektos, meaning molten, these Brazilian tektites represent a relatively recent geological event compared to others, such as the Ivory Coast tektites, which are dated at 1.3 million years.