What is the thin, glassy coating called that forms on the exterior of a small object after it cools rapidly upon slowing down?
Answer
Fusion crust
As a meteoroid rapidly decelerates upon entering the atmosphere, intense heat causes the outer layers to melt and vaporize—a process called ablation. If a fragment survives this violent event, the molten surface material cools down very quickly once sufficient slowing has occurred. This rapid solidification results in the formation of a thin, glassy exterior layer known specifically as a fusion crust. The presence of an intact fusion crust is often the most reliable visual indicator that a dark, dense rock found on the ground is indeed a recent meteorite fall and not a terrestrial rock.
Related Questions
What is the cosmic object called while it is still traveling in space? What is the proper term when the space object enters Earth’s atmosphere and starts burning up? What term is used only after an object survives atmospheric passage and lands on the Earth’s surface? What term sometimes refers to the most spectacular fireballs seen streaking across the night sky? Which category of meteorites, composed primarily of silicate minerals, is the most common type encountered? What primary alloy composition defines Iron meteorites? Which meteorite category is the rarest, containing roughly equal parts silicate minerals and iron-nickel metal? What feature characterizes the Pallasite, an example of a stony-iron meteorite? What is the thin, glassy coating called that forms on the exterior of a small object after it cools rapidly upon slowing down? What is the first recommended action to secure a suspected meteorite specimen regarding contamination? What context about a meteorite fall significantly influences its scientific pedigree and value to collectors?