Thumbprints
Thumbprints is a common name for regmaglypts, the shallow dents on a meteorite's surface that look as if pressed by thumbs.
Many meteorites, especially irons, have shallow dimples on their surface that look as if someone pressed soft clay with their thumbs. Collectors call these thumbprints. Their scientific name is regmaglypts.
They form during atmospheric entry. As the meteoroid's surface melts and is swept away by the rushing air, softer or more easily melted spots and turbulence in the airflow carve out shallow hollows. Iron meteorites such as Sikhote-Alin often show beautiful thumbprints, and some stony meteorites have them too.
Thumbprints are a useful identification clue, because Earth rocks shaped by wind, water or weathering do not usually look like this. However, some weathered rocks have pits that can be confused with regmaglypts. Meteorite thumbprints are smooth, rounded and covered in fusion crust, and they often form patterns that flow across the surface. Rocks with sharp-edged holes or bubbles are more likely to be volcanic or slag.
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Level: Beginner Ages 7 and up