Stony meteorites, the most common type of meteorite, are generally composed of approximately 75 – 90% silicon-based minerals, 10 – 25% nickel-iron alloy, and trace amounts of iron sulfide.
Stony meteorites account for ~94% of observed meteorite falls, and can be divided into two distinct categories: Chondrites and achondrites.
The chondrites take their name from chondrules, the nearly spherical, silicate-rich particles they contain. They are the most abundant type of stony meteorite, and contain some of the first objects to have formed in the Solar System, including calcium-aluminum-rich inclusions (CAIs) and chondrules.
Chondrites have never undergone melting. Their chemistry is very primitive because they have had very few chemical interactions with other objects since their formation.
The most common meteorites found on Earth, chondrites account for approximately 86% of all meteorites recovered.
Achondrites lack chondrules, originate on differentiated planetary bodies (ie planetary bodies with a distinct core and crust), such as asteroids, planets, or moons, and were reformed from molten fragments that were flung into space as the result of another collision.
Because achondrites closely resemble terrestrial rocks to the naked eye, they are less commmonly encountered as finds.
The achondrites include angrites, aubrites, diogenites, eucrites, howardites, lunar meteorites, martian meteorites, primitive achondrites (such as acapulcoites, brachinites, lodranites, and winonaites), and ureilites.
For detailed information on achondrites and their classification, click here.
Click on the images below to learn about some of the achondrites in the ASU Center for Meteorite Studies collection!