Meteorite, also known as "meteorite", is an unburned stone, iron or a mixture of stone and iron, which is scattered on the surface of the earth or other planets by cosmic meteors or dust fragments that deviate from the original orbit outside the earth. Because meteorites are objects from outer space, it is necessary to identify whether meteorites are true or false by instruments, and the naked eye has only an auxiliary role. Most meteorites come from the asteroid belt between Mars and Jupiter, and a few come from the moon and Mars. Meteorites can be roughly divided into stone meteorites, iron meteorites and stone-iron mixed meteorites. The average density of meteorites is between 3 and 3.5, and the main component is silicate. The density of meteorite iron is 7.5~8.0, which is mainly composed of iron and nickel. The composition of stony iron is between them, and the density is between 5.5 and 6.0.