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How are chondrites different from achondrites?
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Meteorite
The Hoba meteorite, lying where it was discovered in 1920 near Grootfontein, Namibia. The largest meteorite on Earth and an iron meteorite by classification, it consists of a nickel-iron alloy and is estimated to weigh about 60 tons.
The fundamental distinction between chondrites and achondrites lies in their thermal history and physical composition.
Thermal History
- Chondrites: These are considered primitive meteorites that have never experienced significant melting. They represent aggregates of material that formed in the solar nebula prior to or during the formation of planets.12
- Achondrites: These meteorites were produced by the melting and crystallization of their parent bodies, such as asteroids, the Moon, or Mars. Consequently, they resemble terrestrial igneous rocks.13
Physical Composition
- Chondrites: They are characterized by the presence of chondrules—small, spherical, silicate-rich inclusions that formed as molten droplets in the early solar system. They are often described as mechanical mixtures of preexisting materials, similar to sedimentary conglomerates.425
- Achondrites: By definition, these meteorites lack chondrules. Their structure is the result of igneous processes rather than the accumulation of primitive solar nebula components.3