How to recognise a meteorite

Fusion crust on a stoney meteorite.

Regmaglypts

Widmanstatten pattern in an iron meteorite.

How to recognise a meteorite.

A good indicator that a rock may be a meteorite is the presence of a fusion crust. This is a thin black or dark brown layer almost like a rind around the outside of the rock. The fusion crust forms as the meteor hurtles through the Earth’s atmosphere, and the resulting friction melts its outer layers.

Meteorites contain metal so feel solid and will often be much heavier than standard crumbly rocks from Earth. This also means that they will be much more difficult to break. If your rock has bubbles or holes in it then it is probably not a meteorite; look for smooth rocks.

You may be able to see distinctive patterns in the surface of the rock. As they fall through the atmosphere your space rocks are buffeted by the atmosphere. Some may become streamlined by the journey if they fall “nose down” and assume an aerodynamic shape.

Others will display strange lumps and depressions as a result of a “tumbling” entry to our atmosphere. These markings (regmaglypts) are peculiar to meteorites, and they look very much like thumbprints in clay. When sliced open, some types of meteorite display unusual and beautiful structures.

Meteorites are ferromagnetic, meaning that they will attract a magnet. The stronger the magnet, the better and you can rig up a very basic but effective “magnet on a string” type affair to help you locate possible meteors in the field. If you’re feeling that this is a little too small scale for your liking, you could copy the great H.H. Nininger, who used to tow a magnetic rake behind his car.

From - Esther Gauld, Geeks.co.uk