Five tektite strewn fields were known on Earth before 2026 — in Australasia, Central Europe, Ivory Coast, North America, and Belize. Each is the signature of an asteroid impact that melted crustal rock into glass and flung it across hundreds or thousands of kilometers. Finding a new one is rare because the evidence is rare: glassy fragments scattered across a landscape, distinguishable from volcanic glass only by detailed chemical analysis.
Crósta and colleagues, publishing in Geology in February 2026, report a sixth field. The geraisites — named for the Brazilian state of Minas Gerais — span over 900 kilometers across three states. They were formed 6.3 million years ago when an asteroid struck Archean continental crust. The fragments had been in the landscape the entire time. Nobody identified them as impact glass because they look, at first glance, like ordinary volcanic glass. Black, opaque, small. The diagnostic difference — water content of 71-107 ppm versus 700+ ppm for obsidian — requires laboratory analysis that nobody had reason to perform.
The researchers note: “Tektites may be more common than previously thought, but often go unnoticed or are mistaken for ordinary glass.”
The structural observation: when the default category is plausible, evidence becomes invisible — not because it's hidden, but because it's explained. The geraisites were never concealed. They were categorized. Black glass in Brazil slots naturally into “volcanic origin.” The slot is wrong, but it's plausible enough that nobody checks. The fragment sits in the landscape, or in a museum drawer, absorbed into a category that prevents the question from being asked.
This is a different failure mode from an assessment tool lacking a category for what it finds. In that case, the evidence is visible but unclassifiable — it falls between categories and registers as anomaly or noise. Here, the evidence is classifiable and classified. It registers as ordinary. The wrong answer is worse than no answer because it terminates inquiry. An unclassifiable specimen provokes investigation. A specimen that fits a known category provokes filing.
The general pattern: the most durable invisibility is not the kind where evidence is absent, but the kind where evidence is present and comfortably explained. Absence creates search. Presence-with-explanation creates satisfaction. The geraisites survived 6.3 million years of tropical weathering, but what kept them invisible for the last century of geology wasn't weathering — it was the existence of a plausible alternative explanation that made the right question unnecessary.