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What are the three main groups of meteorites?
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Small body
Asteroid Ida and its satellite, Dactyl, photographed by the Galileo spacecraft on August 28, 1993, from a distance of about 10,870 km (6,750 miles). Ida is about 56 km (35 miles) long and shows the irregular shape and impact craters characteristic of many asteroids. The Galileo image revealed that Ida is accompanied by a tiny companion about 1.5 km (1 mile) wide, the first proof that some asteroids have natural satellites.
Meteorites are traditionally classified into three primary groups based on the proportions of rock-forming minerals and nickel-iron metal they contain. These categories are:1
- Stony meteorites: Composed largely of silicate minerals, these are the most abundant type, accounting for approximately 94 percent of all known meteorites. They are further divided into chondrites and achondrites.12
- Iron meteorites: Consisting primarily of nickel-iron metal, these represent about 5 percent of meteorites. They are believed to originate from the metallic cores of differentiated parent asteroids.13
- Stony iron meteorites: These are an intermediate type containing substantial amounts of both silicate rock and nickel-iron metal. They make up about 1 percent of all known meteorites and include groups such as pallasites and mesosiderites.41
While these categories help organize meteorites by their observable composition, researchers often look at chemical and mineralogical subdivisions to better understand the diverse origins and histories of these objects.1