This rusting starts out as small red and orange spots on the surface of the meteorite that slowly expand to cover more and more of the rock. You may still be able to see the black crust even if part of it has begun to rust. [2] X Research source The meteorite may be black in color but with slight variations (e. g. , steely bluish black). However, if the rock you’ve found isn’t at all close to black or brown in color, then it is not a meteorite.
Although irregular in shape, most meteorites will have edges that are rounded rather than sharp. [5] X Research source If the rock you’ve found is relatively normal in shape, or is round like a ball, it may still be a meteorite. However, the vast majority of meteorites are irregular in shape.
A fusion crust will most likely be smooth and featureless, though it may also include ripple marks and “droplets” where molten stone had moved and resolidified. If your rock does not have a fusion crust, it is most likely not a meteorite. The fusion crust may look like a black eggshell coating the rock. [8] X Research source Rocks in the desert will sometimes develop a shiny black exterior that looks similar to fusion crust. If you found your rock in a desert environment, consider whether its black surface might be desert varnish.
Flow lines may be small or not immediately apparent to the naked eye, as the lines can be broken or not completely straight. Use a magnifying glass and a discerning eye when looking for flow lines on the surface of a rock. [10] X Research source
Iron meteorites are particularly susceptible to irregular melting and will have deeper, more defined cavities, whereas stony meteorites may have craters that are smooth like the rock’s surface. [12] X Research source These indentations are technically known as “regmaglypts,” though most people who work with meteorites will suffice to call them “thumbprints. ”
If the rock you’ve found has holes in the surface, or appears “bubbly” as if it was once molten, it is definitely not a meteorite. [14] X Research source Slag from industrial processes is often confused for meteorites, although slag has a porous surface. Other commonly mistaken types of rock include lava rocks and black limestone rocks. If you’re having trouble discerning between holes and regmaglypts, it may be useful to view side-by-side comparisons of these features online to learn how to spot the difference. [15] X Research source
You can calculate the density of the potential meteorite by dividing its weight by its volume. If a rock has a calculated density higher than 3 units, it is much more likely to be a meteorite. [17] X Research source
Because many terrestrial rocks are also magnetic, the magnet test will not definitively prove your rock is a meteorite. However, failing to pass the magnet test is a very strong indication that your rock is probably not a meteorite. An iron meteorite will be much more magnetic than a stone meteorite and many will be strong enough to interfere with a compass held close to it. [20] X Research source
For an unglazed ceramic tile, you can use the unfinished bottom of a bathroom or kitchen tile, the unglazed bottom of a ceramic coffee mug, or the inside of a toilet tank cover. [22] X Research source Hematite and magnetite rocks are commonly mistaken for meteorites. Hematite rocks leave a red streak, while magnetite rocks leave a dark gray streak, indicating that they are not meteorites. [23] X Research source Keep in mind that many terrestrial rocks also do not leave streaks; thus, while the streak test can rule out hematite and magnetite, it will not definitively prove your rock is a meteorite on its own.
You’ll need a diamond file to ground down the surface of a meteorite. The filing process will also take some time and a good bit of effort. If you’re unable to do this on your own, you can take it into a laboratory for specialist testing. [25] X Research source If the interior of the rock is plain, it is most likely not a meteorite.
Although chondrules are generally located in the interiors of meteorites, weather erosion may cause them to be visible on the surface of meteorites that have been exposed to the elements for a sufficient amount of time. In most cases, you will need to break open the meteorite to check for chondrules. [27] X Research source
