Properties of meteorites that are useful in identification

Meteorites are:

HEAVY: Most meteorites contain a significant amount of Fe-Ni metal, and are thus heavier (high-density) than rocks typically found at the surface of the Earth.  There are exceptions to this rule.  Some meteorites contain no metal at all, and are about as heavy as the dark volcanic rocks found in Hawaii and the Columbia Gorge.

MAGNETIC:  Most meteorites contain a significant amount of Fe-Ni metal, and are attracted to a magnet. Again, there are a few exceptions of stony meteorites that contain no metal and are not attracted to a magnet.

IRREGULAR IN SHAPE: Meteorites aren't round.  If a meteorite has entered the Earth's atmosphere without rotating, it can develop a conical shape similar to the reentry capsules used in the Apollo space missions, although this is not typical.  Most meteorites are irregularly shaped, as shown by the five views of CML 0023 (an unclassified North African meteorite) below.  The second image from the right shows the start of what could be considered an aerodynamic shape.

COVERED BY A FUSION COATING: When a meteorite enters the Earth's atmosphere, friction raises the surface of the meteorite above its metling temperature.  As the meteorite descends, it slows down, frictional heating decreases, and the melt quenches to form a fusion coating, a thin layer of dark glass. The fusion coating may be black or brown, dull or shiny on a recently fallen meteorite.  After the meteorite has been on the Earth's surface for a while, the fusion coating may rust, giving the outside of the meteorite a reddish-brown coloring, or the fusion coating may erode off partially or completely.  The fusion coating is a thin, discrete layer surrounding an interior that looks quite different from the fusion coating.  Some Earth rocks can develop a weathing rind (from chemical weathering) on their exteriors that is similar in appearance to a fusion coating.  However, there is rarely a sharp boundary between a weathering rind and the interior of the rock.  Many meteorites's surfaces develop shallow pits during entry into the Earth's atmosphere.  These pits, known as regmaglypts, resemble thumb prints, and are usually better developed on iron meteorites than on stony meteorites.
 

Forest City (H5 ordinary chondrite) is covered by a fusion coating.  In the picture below, one tip has been cut off, exposing the lighter gray and speckled interior of the meteorite.  The fusion coating is very thin.	Another view of Forest City, showing that a small ridge of metal is protruding from the fusion coating (slightly to the right of the center of the image).  There are small indentations/pits on the surface of the meteorite.
Below is Allende (CV3 carbonaceous chondrite).  Patches of the fusion coating have worn off, exposing the lighter gray and speckled interior.	Below is the Gibeon (IVA) iron meteorite, showing well-developed regmaglypts (thumbprints) on the surface of the meteorite.
Below is the rusty weathered fusion coating on the Millbillillie (eucrite achondrite) meteorite.	Below is the interior of the same sample of Millibillillie as at left.  Notice again the thinness of the fusion coating and the distinctly different interior.

SOLID AND COMPACT:  Most meteorites do not have the bubbly texture (vesicular) that is often found in many volcanic rocks on Earth.  There are a few exceptions to this rule.

DIFFERENT FROM THE OTHER ROCKS IN THE AREA:  Many meteorites are composed entirely or in large part of metal.  These are obviously different from the rocks found on the Earth's surface.  The stony meteorites are different in appearance from most types of Earth rocks, but unfortunately are similar in appearance (at least with a fusion crust) to the dark volanic rocks that are common in Oregon and Washington.