All articles tagged with #geraisites
Scientists have identified hundreds of tektites—glass droplets formed when a meteorite melted surface rock—over a 900-km region in Brazil, named geraisites. Dating places the material up to about 6.3 million years old and reveals an ancient crustal source from the São Francisco Craton. No nearby crater has been found, but the discovery expands Brazil's impact history and suggests tektites may be more common than previously thought.
A 900-km-wide field of tektites—natural glass formed by a meteorite impact about 6.3 million years ago—has been identified across Minas Gerais, Bahia, and Piauí in Brazil, with about 500 specimens collected and named geraisites. The glass is silica-rich and extremely dry, providing new clues about South America’s ancient impact history, though the crater responsible has not yet been found (likely somewhere in the São Francisco Craton).
Scientists have identified a new tektite strewn field in northeastern Brazil, named geraisites after Minas Gerais, with roughly 500–600 glassy specimens spanning about 900 km. Dating places the impact at about 6.3 million years ago, near the Miocene end, when a large meteorite melted surface rocks and ejected glass that cooled into tektites (silica-rich with lechatelierite inclusions). The geraisites are 1–86 g, often black but turning gray-green in light, with surfaces marked by cavities from atmospheric entry. The field has expanded beyond the initial zone, but the crater has not yet been found and may lie buried or eroded in the São Francisco craton; satellites may help locate it. There are only a handful of tektite fields known worldwide.
Brazilian researchers identified a new tektite field, geraisites, from a 6.3-million-year-old meteor impact that spread tektites over roughly 900 km in Minas Gerais and neighboring states; analyses of silica content, low water, lechatelierite inclusions, and argon-argon dating place the event in the late Miocene, with a buried São Francisco Craton crater likely as the source.