Meteorites are usually named for the post office or a large geographic landmark closest to the fall or find, collectively termed localities. The recovered mass of meteorites represents some of the scarcest material on Earth, much rarer than gold, yet presents us with some of the original material from which the entire Earth was formed. Because of their scarcity and their primitive origins, meteorites are sought after by collectors and researchers alike. Most chondrites have remained unchanged since their formation 4.56 billion years ago, shortly after the formation of the Sun. Almost all chondrites contain chondrules - small, gaseous, spherical inclusions that formed during the solar nebula.
Achondrites appear to have been chondritic before being altered by a heating or impact event.
These meteorites are much rarer than chondrites and include the HED group from asteroid 4 Vesta and SNCs from the planet Mars. Iron meteorites are thought to be pieces of the shattered cores of differentiated asteroids and contain varying amounts of nickel. Octahedrites containing 6.5 to 13 percent nickel and Ataxites with nickel amounts of 16 to 30 percent. Iron meteorites are the most common group of meteorites by weight. Mesosiderites and Pallasites are the two main groups of the stony-iron meteorites.