Many of you have heard or even seen a meteorite. It is a solid piece of debris from objects like an asteroid, a comet, or a meteoroid, and has its origins in outer space. It passes through the atmosphere and reaches the surface of a planet or its moon. At the time when an original meteorite enters the atmosphere, factors like pressure, friction, as well as chemical reactions with the gases present in the atmosphere heat it. As a result, a meteorite radiates energy. Gradually, it becomes a meteor and a fireball is formed. This is what you know as a falling star or a shooting star. After making their way into the Earth’s atmosphere, meteorites tend to disintegrate. The ones that fall on the earth’s surface are recovered by scientists. But how would you know that the rock in question is a meteorite? Check out.
There will be a trace of metal in the majority of meteorites. If you observe any metal shining on the broken surface of a rock, you probably are looking at a meteorite.
All meteorites are known to have some metals present in them. If there is a presence of a lot of metal in a meteorite, its density will be much more in comparison to the regular rocks. If you have a rock that has a higher density, you might have a meteorite. However, not all meteorites have a higher density.
There are traces of iron-nickel metal in many meteorites. The presence of iron in the rock can attract a magnet. Does the sample or rock attract a magnet? If yes, the rock in question might be a meteorite. With that being said, several natural rocks have magnetic properties. Therefore, even if your rock happens to attract magnets, it doesn’t necessarily imply that it is a meteorite.
Meteorites from primitive ages have pieces of a stony material in them, basically round in shape. These pieces are known as chondrules. If the rock contains such round pieces of stony material, then you probably have come across a meteorite. But some spherical particles, resembling chondrules, can be present in volcanic and sedimentary rocks as well.
The massive compression of the atmosphere causes the meteorite to heat up while it is falling through the atmosphere. As the meteor gets hotter, its outer surface starts melting. This results in the formation of a brown or black coating on the rock’s surface. This coating is called a fusion crust. Traces of melted metal can be visible on the surface of iron meteorites. However, that might not be the case every time. Meteorites that have fallen recently can exhibit fusion crusts. The crusts are fragile and tend to weather away from the surface of rocks that have fallen through long ago. If you look closely into the hollows of the rock sample, you might find small patches of fusion crust. If your rock has a fusion crust, it can be a meteorite.
As a meteorite enters the atmosphere, the temperature of its surface begins to rise and starts melting. However, some portions get melted more than others and as a result, erode. The eroded portions look like someone has taken out small scoops of the material from that part. Left behind is a group of small dents on the surface that look as if you have put your thumbprints on clay. These thumbprints are present on a majority of the meteorite samples and are called regmaglypts. The size of the regmaglypts can lie in the range of less than a centimeter to 10 centimeters.
As per various studies on meteorites, they generally don’t leave a streak. However, you can find a reddish streak on the surface of some meteorites if they have been oxidized, or in other words, rusted. By dragging the sample of rock across the so-called streak plate, you might notice a red or orange line. In that case, the sample of rock might be hematite, a common mineral found on Earth. Now, if the same has magnetic properties and leaves a black or gray streak, it might be magnetite, an iron-oxide mineral. If your sample doesn’t leave a streak, then you probably have a meteorite in your collection.
Meteorites are pretty rare. When people come across unusual pieces of rock, they think they have got a meteorite. However, the above said steps can only verify if the samples are indeed meteorites or not.