When the meteorite is flying at high altitude, the surface temperature of the meteorite reaches thousands of degrees. At such a high temperature, the surface of the meteorite melts into a liquid. Later, due to the obstruction of the lower layer of thicker atmosphere, his speed became slower and slower, and the melting surface cooled down to form a thin shell called the "melt shell". The shell is very thin, usually around 1 millimetres, and the color is black or brown. In the process of cooling the molten shell, the trace of the air flowing through the surface of the meteorite is also retained, called "gas seal". The air print looks like the finger printed on the dough. The main features of the surface of the meteorite are the molten shell and gas print. If you see the surface of stone or iron has a layer of melted shell or gas seal, you can immediately conclude that this is a meteorite. But some meteorites that fall down for a long time are not easy to identify the gas seals due to long wind, sun and rain. But that doesn't matter. There are other ways to identify them..
The stone meteorite looks much like the rock on the earth and weighs it by hand and thinks it is heavier than the same volume of rock. Stone meteorites usually contain a few percent of iron, magnetic, magnet it will feel. In addition, a careful look at the cross section of the stone meteorite will find a lot of small pellets. The pellets usually have about 1 millimeters or more than 2~3 millimeters. More than 90% of the stone meteorites have such chondrules, which were produced when meteorites were formed. It is an important marker for identifying stone meteorites. Iron and nickel are the main components of the iron meteorites. Among them, iron accounts for about 90%. The content of nickel is generally between 4~8%, and the content of nickel in the earth's natural iron is generally not so much.