Meteorites are fragments of rock or metal that fall to Earth from space. They are very rare, but many people find unusual rocks or pieces of metal and wonder if they might have found a meteorite. The USGS doesn't verify meteorites, but they have several properties that help distinguish them from other rocks:
- Density: Meteorites are usually quite heavy for their size, since they contain metallic iron and dense minerals.
- Magnetic: Since most meteorites contain metallic iron, a magnet will often stick to them. For “stony” meteorites, a magnet might not stick, but if you hang the magnet by a string, it will be attracted.
- Unusual shape: iron-nickel meteorites are rarely rounded. Instead, they have an irregular shape with unusual pits like finger prints in their surface called “regmaglypts.”
- Fusion crust: stony meteorites typically have a thin crust on their surface where it melted as it passed through the atmosphere.
Meteorites do NOT have the following:
- Light-colored crystals: Quartz is a common, light-colored crystal in Earth’s crust, but it is not found on other bodies in the solar system.
- Bubbles: volcanic rocks or metallic slag on Earth often have bubbles or vesicles in them, but meteorites do not.
- Streak: if you scratch a meteorite on an unglazed ceramic surface, it should not leave a streak. A dense rock that leaves a black or red streak probably contains the iron minerals magnetite or hematite, respectively, neither of which are typically found in meteorites.
These tips for identifying a meteorite were adapted from this excellent guide from the University of New Mexico Meteorite Museum. Please refer to their site for additional information.
Rocks and minerals--including potential meteorites--must be examined in person for proper identification. For suggestions on where to do that, see: Can you identify my rock or mineral?