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Chondrite Meteorite

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Chondrites, the most common meteorites, are named for the little round grains—chondrules—that make them up. Chondrules formed before any planets. (more below)
The commonest space rock
Photo (c) 2006 Andrew Alden, licensed to About.com (fair use policy)
Chondrites (KON-drites) are the most common type of meteorite. They get their name from the strange little particles they're made of, called chondrules. Under the microscope these can be seen to be tiny balls of the minerals olivine and pyroxene, which form at very high temperatures. They are the oldest rocks, even older than Earth itself. (Some particles of space dust are older still.)

Chondrites are evidence of a period when the sun was being born and the great cloud of mineral dust around it was gathering into bodies, as large across as a few kilometers, called planetesimals. They were hot, they bumped together, and eventually grew into small planets. At that point their great heat melted all the material, wiping out the signs of its earlier history. (more about solar system formation) Chondrites escaped that melting and survived to the present day, mostly in the asteroid belt.

This chondrite is part of a group of meteorites that was found in Algeria in 1999. It is a broken piece of a larger stone, and we are looking at the broken inner part. The left edge shows the curved and polished outer rind, which formed as the meteorite sped through the Earth's atmosphere. Most meteorites are larger than small pebbles, because smaller ones burn up completely.

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