Chondrites are meteorites named after the small stony spheres that compose them, called chondrules. The carbonaceous chondrites are almost completely or completely oxidized and contain the most volatile elements and the largest amount of organic compounds. The most primitive chondrites, the carbonaceous or C chondrites, are can be further divided into six petrographic subgroups.
Achondrites are stony meteorites that lack chondrules.
Most meteorites come from asteroids in the asteroid belt between Mars and Jupiter . Others come from the Moon or Mars after ejecta from a meteorite impact is blown into space. All meteorites seemed to have formed within a relatively short period of 5-20 million years, forming 4.55 billion years ago. Chondrites are believed to have formed during the early formation of the solar system, and are important because they contain an undisturbed record of the accretionary and preaccretionary solar system. Their composition is much like that of the sun.