If you ever come across a rock that looks like it is from another world, there is a chance that it is a meteorite. Even though these are relatively rare on Earth, it still wouldn't be impossible for you to find one in the wild. However, you want to be sure that what you have found is indeed a stone or rock containing iron of cosmic origin and not just a piece of any earthly material. You can look at some common physical and visual markings on meteorites to determine if the rock you have found really has an extraterrestrial origin.
Part 1 of 2: Find Visual Features
Step 1. See if the rock is black or rusty brown
If the rock you have found is a meteorite that has recently fallen, its appearance will be shiny black since its passage through the atmosphere will have burned it. However, after a long period of time on Earth, the iron in the meteorite will begin to rust and its appearance will turn rusty brown.
- The oxidation begins with small red and orange dots on the surface of the meteorite that then expand to completely cover the rock. However, you will still be able to see the black scab even if some part of it has started to rust.
- A meteorite is black in color, but it can also have some variations (for example, bluish steel black). If the rock you found is nowhere near black or brown, then it is not a meteorite.
Step 2. Confirm that the rock has an irregular shape
Unlike what you can generally imagine, most meteorites are not spherical, on the contrary, they almost always have irregular shapes with edges of different sizes and shapes. Although some meteorites may acquire a conical shape, most will not appear aerodynamic after landing.
- Despite their irregular shape, most meteorites will not have sharp edges but rather rounded ones.
- If the rock you found is relatively normal in shape or round like a ball, it may still be a meteorite; however, the vast majority of them have irregular shapes.
Step 3. See if the rock you found has a melt crust
The surface of the rocks that pass through the earth's atmosphere begins to melt and the air pressure forces them to melt again, this produces a surface with a melted appearance called a fusion crust. If the rock you found appears to have melted and displaced, it may be a meteorite.
- The fusion crust is generally smooth and without any peculiarity; however, it may include some wave and drop marks where the rock has melted and re-solidified.
- If the rock does not have a fusion crust, it is most likely not a meteorite.
- The melting crust looks like a black eggshell that lines the rock.
- Desert rocks sometimes develop a black surface that resembles the melt crust. If you have found a rock in the desert, be aware that its black surface may be just the varnish of the desert.
Step 4. Check for flow lines where the rock may have melted
Flow lines are small “ridges” in the melt crust that are caused by melting and backward movement of the material. If the rock has a surface that resembles a crust with small ridges running through it, there is a high probability that it is a meteorite.
Flow lines can be small and imperceptible to the naked eye since they may be interrupted or not completely straight. Use a magnifying glass and a close look to find the flow lines on the rock's surface
Step 5. Identify any holes or depressions in the rock's surface
Although the surface of a meteorite usually has no peculiarities, sometimes it can include shallow holes and deep cavities that resemble fingerprints, these marks in the rock will help you to know if it is a meteorite and what type. of meteorite is.
- Metallic meteorites are particularly susceptible to irregular melting so they will present deeper and more defined cavities whereas stony meteorites can have craters smooth like the surface of a rock.
- These indentations are technically known as "regmagglipts," but most people who work with meteorites call them "fingerprints."
Step 6. Make sure the rock is not porous or has too many holes
Although craters and cavities on the surface may indicate that the rock is a meteorite, none of them have holes inside. Meteorites are solid, dense pieces of rock, if the rock you've found looks porous or full of bubbles, unfortunately it's not a meteorite.
- If the rock you've found has holes in the surface or appears to have bubbles as if it had ever melted, it is definitely not a meteorite.
- Industrial waste is sometimes mistaken for meteorites despite having porous surfaces. Other rocks that are commonly mistaken for meteorites are lava rocks and black limestone rocks.
- If you have difficulties differentiating holes from regmagglipts, it may be useful to see parallel comparisons of these characteristics on the internet and thus learn how to differentiate them.
Part 2 of 2: Testing the Physical Properties of Rock
Step 1. Calculate the density of the rock if it feels heavier than normal
Meteorites are solid pieces of rock that are normally densely mixed with metal. If the rock you found looks like a meteorite, you can compare it to other rocks to make sure it is heavier, and then calculate its density to determine if it really is a meteorite.
You can calculate the density of a potential meteorite by dividing its weight by its volume; if the rock has a density greater than 3 units, it is most likely a meteorite
Step 2. Use a magnet to check if the rock is magnetic
Almost all meteorites are at least a little magnetic, even faintly. This is due to the high concentration of iron and nickel, magnetic in nature, that most meteorites present. Therefore, if the rock does not attract the magnet, it means that it is not a meteorite.
- Many terrestrial rocks are also magnetic, which is why this test is not definitive; however, if the magnet test fails, it would establish a strong indication that the rock is probably not a meteorite.
- A metallic meteorite will be much more magnetic than a rock one, and many of them will be powerful enough to interfere with a nearby compass.
Step 3. Scrape the rock against unglazed ceramic to see if it leaves a scratch
The scratch test is a good way to rule out whether the rock has earth materials. Scrape it against a piece of unglazed ceramic tile, if it leaves a streak stronger than a faint grayish line, it is not a meteorite.
- You can use the unfinished bottom of a bathroom or kitchen tile, the unglazed base of a ceramic mug, or the inside of a toilet tank lid.
- Hematite and magnetite are rocks that are often mistaken for meteorites. Hematites leave a red streak while magnetites leave a dark gray streak; all this indicates that they are not meteorites.
- Note that many ground rocks also do not leave streaks. While the streak test can rule out hematite and magnetite, it will not definitively prove that the rock is a meteorite.
Step 4. File the surface of the rock and look for shiny metal flakes
Most meteorites contain metal that can be seen glowing below the surface of the melting crust. Use a diamond file to file one corner of the rock and check for metal markers inside.
- You will need a diamond file to file the surface of the meteorite, and this process can take some time and a bit of effort. If you can't do it alone, you can take it to a lab for specialized tests.
- If the interior of the rock is flat, it is most likely not a meteorite.
Step 5. Inspect the inside of the rock for small balls of stony material
Most meteorites that fall to Earth are the type that have small round masses inside called chondrules. These look like small stones of different sizes, shapes and colors.
- Although chondrules are normally found inside meteorites, weathering erosion can cause them to be visible on the surface of those who have been exposed to the elements of the weather for a long time.
- In most cases, you will have to break the meteorite to look inside for the chondrules.
- Meteorites have bubbles called vesicles. All lunar meteorites are vesicular; metallic and stony meteorites do not have bubbles on the inside and some stony meteorites have bubbles on the outside.
- Because of the high concentrations of nickel in meteorites, you can use a nickel test to determine whether or not the rock you have is a meteorite. This test can be done in any meteorite testing laboratory and will be more definitive than any of the other tests described above.
- There are many books and websites that you can learn about.
- The chances of finding a true meteorite are very small; But if you want to find one, deserts are the best places to look.