Geology and Minerals

Chondrite

A chondrite (, CON-drite) is a stony (non-metallic) meteorite that has not been modified by either melting or differentiation of the parent body. They are formed when various types of dust and small grains in the early Solar System accreted to form primitive asteroids. Some such bodies that are captured in the planet's gravity well become the most common type of meteorite by arriving on a trajectory toward the planet's surface. Estimates for their contribution to the total meteorite population vary between 85.7% and 86.2%. Their study provides important clues for understanding the origin and age of the Solar System, the synthesis of organic compounds, and the origin of life and the presence of water on Earth. One of their characteristics is the presence of chondrules (from the Ancient Greek χόνδρος chondros, grain), which are round grains formed in space as molten or partially molten droplets of distinct minerals. Chondrules typically constitute between 20% and 80% of a chondrite by volume. Chondrites can be distinguished from iron meteorites by their low iron and nickel content. Non-metallic meteorites that lack chondrules are achondrites, which are believed to have formed more recently than chondrites. There are currently over 27,000 chondrites in the world's collections. The largest individual stone ever recovered, weighing 1770 kg, was part of the Jilin meteorite shower of 1976. Chondrite falls range from single stones to extraordinary showers consisting of thousands of individual stones. An instance of the latter occurred in the Holbrook fall of 1912, in which an estimated 14,000 stones were grounded in northern Arizona.

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See also

• ▸Grand Staircase–Escalante National Monument
• ▸Health in Pakistan
• ▸Chaîne des Puys

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