How to Identify Meteorites: Photos Guide

Found a Rock From Out of This World? Have you stumbled upon a rock that seems strangely heavy or different from others you've seen? It might just be a visitor from space! Meteorites, remnants of asteroids, comets, or even planets, occasionally fall to Earth and can be exciting discoveries. But how can you tell if your rock is truly a meteorite?

Types of meteorites

Here's a step-by-step guide to help you determine if a rock is a meteorite:

Physical Characteristics

Weight and Density

Meteorites are usually denser than common rocks. Pick up the rock. If it feels unusually heavy for its size, it could be a meteorite.

Magnetism

Many meteorites contain iron and nickel, making them magnetic. Use a strong magnet (not a refrigerator magnet) to see if the rock isattracted to it. However, not all meteorites are magnetic, so a negative result doesn't rule it out.

Meteorite Magnetism

Exterior Appearance

Fusion Crust

Fusion Crust is a thin, black, glassy coating that forms on the meteorite's surface during its fiery entry into the atmosphere. It may be smooth or have melted bumps. Not all meteorites have a complete fusion crust, but its presence is a strong indicator.

Meteorite Fusion surface

Regmaglypts

Regmaglypts are shallow fingerprint-like depressions or indentations that form on the surface of some meteorites as they travel through Earth's atmosphere at high speeds. Swirling hot gas carves these smooth indentations. They aren't on every meteorite, depending on factors like size and entry angle. But their presence is a key clue for scientists studying a meteorite's extraterrestrial origins.

Regmaglypts in meteorites

Examine the shape

Meteorites won't be perfectly round or smooth. They'll often have irregular shapes with melted or pitted surfaces. This is caused by the intense heat and pressure they experience during atmospheric entry.

Meteorite shape

Color

Fresh Falls: These meteorites will typically have a black or dark brown colored exterior due to the presence of a fusion crust.
Weathered Meteorites: Over time, a weathered meteorite will lose its fusion crust due to exposure to the elements. This can cause the meteorite to develop a rusty appearance or take on a reddish-brown color. This rusting is caused by the oxidation of iron within the meteorite.

Meteorite Color

Interior Examination

Cut a Small Sample

If possible, cut a small piece of the rock to examine the interior. Meteorites often have a different appearance inside compared to the outside. It's important to note that cutting a meteorite is destructive and should only be done on small, non-museum quality specimens.

Cut a Small Sample of meteorite

Metallic Flecks

Shiny, metallic grains within the rock are a strong indication of iron and nickel, common components in meteorites.

Meteorite Metallic Flecks

Chondrules

If the meteorite is a chondrite (the most common type), you might see small, round mineral inclusions called chondrules. These are believed to be the building blocks of planets and asteroids.

Chondrules Meteorites

Widmanstätten Patterns

This is a special feature seen only in iron meteorites. When a polished surface of an iron meteorite is etched with a mild acid, it reveals a beautiful, interwoven crystalline structure called a Widmanstätten pattern. This pattern is a result of the slow cooling of iron and nickel within the meteorite over millions of years.

Widmanstätten Patterns meteorite

Chemical Composition

Nickel Test: Meteorites often contain nickel. Use a chemical test kit to check for the presence of nickel.

Expert Verification

Contact a Meteorite Expert: If your rock passes the initial tests, contact a meteoritics laboratory, museum, or university with a geology or planetary science department. They can provide a definitive analysis.

Submit for Classification: If confirmed, you can submit the meteorite for classification and official documentation.

Tips and Warnings

Be Cautious with Assumptions: Many terrestrial rocks can mimic meteorite characteristics, such as slag from industrial processes.

Preserve the Sample: Handle the rock minimally to avoid contamination and preserve its characteristics for accurate testing.

Summary

Visual Inspection: Look for fusion crust, shape, surface features.
Magnet Test: Check for magnetism.
Density Test: Compare weight and density.
Streak Test (optional): Perform a streak test on ceramic.
Interior Examination: Look for metallic flakes and chondrules.
Chemical Testing: Test for nickel and reaction with acid.
Professional Verification: Seek expert analysis and laboratory testing.

By following these steps, you can systematically determine if a rock is a meteorite. However, the final confirmation often requires expert analysis to rule out all possibilities of terrestrial origin.