New England Meteoritical Services

What Are Meteorites?

Meteorites are pieces of other bodies in our solar system that make it to the ground when a meteor or "shooting star" flashes through our atmosphere at speeds of 15 to 70 kilometers per second (roughly 32,000 to 150,000 miles per hour). The majority originate from asteroids shattered by impacts with other asteroids. In a few cases they come from the Moon and, presumably, comets and the planet Mars. Meteorites that are found after a meteoric event has been witnessed are called a "fall," while those found by chance are called a "find." Meteorites are usually named after a town or a large geographic landmark closest to the fall or find, collectively termed localities. The word "meteorite" can refer to an individual specimen, to those collected within a strewnfield, or to a specific locality.

Lowicz, Poland, mesosiderite.

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.

There are three major types of meteorites: stone, iron and stony-iron.

Parnellee, India, an LL3 stone meteorite

Stone meteorites consist of two groups: chondrites and achondrites. 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.

Ghubara, Oman, an L5 chondrite

Iron meteorites are thought to be pieces of the shattered cores of differentiated asteroids and contain varying amounts of nickel. This type comprises the three basic groups: Hexahedrites that contain 4.5 to 6.5 percent 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.

A stunning display of chondrules in this image of Axtel, Texas, USA. Axtel is a carbonaceous chondrite.

Mesosiderites and Pallasites are the two main groups of the stony-iron meteorites. Mesosiderites consist of broken angular fragments of mantle rock and nickel-iron that have been fused together by impacts with another body. Pallasites, some of the most attractive meteorites, are believed to have formed at the core-mantle boundary of asteroids and contain crystals of olivine (peridot).

Camel Donga, Australia. 633 gram end piece. Camel Donga is a eucrite achondrite.


New England Meteoritical Services