Tektite

Tektite is a natural glass formed from terrestrial rock melted and ejected during a high-velocity meteorite impact, then quenched in flight. Tektites form during hypervelocity meteorite impacts. When a large meteorite strikes the Earth, the enormous energy melts and vaporizes both the meteorite and the target rock. Molten material is ejected at high speed into the upper atmosphere or even briefly into space, where it cools rapidly into glass as it falls back to Earth.

Different impact events created different tektite strewn fields. The Australasian field (the largest and youngest, ~790,000 years old) covers Southeast Asia to Australia. The Central European field produced moldavites (~15 million years old) from the Ries crater impact in Germany. The North American field (~35 million years old) is associated with the Chesapeake Bay impact.

The aerodynamic shapes of tektites (spheres, dumbbells, teardrops, discs) result from their spinning while molten during flight. Splash-form tektites cooled while spinning in the air. Layered tektites (Muong Nong type) solidified as thick, layered pools from material that didn't travel as far.

Tektites are glassy, usually black or very dark, and feel lighter than expected for their size. Surface textures include pitting, grooves, and sculptured forms from atmospheric ablation. Splash-form tektites have distinctive aerodynamic shapes.

Distinguish from obsidian (which has flow banding and is volcanic, not impact-related), slag (typically has metallic inclusions and irregular vesicles), and artificial glass (too uniform). Tektites are virtually free of crystalline inclusions and water content, unlike volcanic glasses.