World Library  
Flag as Inappropriate
Email this Article

Ordinary chondrite

Article Id: WHEBN0003276170
Reproduction Date:

Title: Ordinary chondrite  
Author: World Heritage Encyclopedia
Language: English
Subject: Agen (meteorite), Akbarpur (meteorite), Albareto (meteorite), Allegan (meteorite), Ambapur Nagla
Publisher: World Heritage Encyclopedia

Ordinary chondrite

Ordinary chondrite
— Class —
Ordinary chondrite NWA 869
Compositional type Stony
Type Chondrite
Parent body unknown
Alternative names O chondrites
Ordinary chondrite NWA 3189 sliced. Field of view ~2.2 cm across. NWA 3189 has been classified as an LL3.2-3.4 ordinary chondrite (“LL” means very low total iron content; “3” refers to well-preserved chondrules - the rock has not been subjected to metamorphism intense enough to disrupt the chondritic texture). This chondrite has a nice, multicolored mix of chondrules of varying size and shape.
Ochansk Meteorite, an ordinary chondrite with a fusion crust, found in 1887 in Russia.

The ordinary chondrites (sometimes called the O chondrites) are a class of stony chondritic meteorites. They are by far the most numerous group and comprise about 87% of all finds.[1] Hence, they have been dubbed "ordinary". The ordinary chondrites are thought to have originated from three parent asteroids, with the fragments making up the H chondrite, L chondrite and LL chondrite groups respectively.[2]


  • Origin 1
  • Chemical composition 2
  • See also 3
  • References 4
  • External links 5


It is suspected that they are not representative of typical asteroid parent bodies, but rather of a select few which are advantageously placed to send impact fragments to Earth-crossing orbits. Such positions are e.g. near Kirkwood gaps and/or secular resonances in the main asteroid belt. In fact, only the one rather insignificant asteroid 3628 Božněmcová has been identified to have a spectrum close to the ordinary chondrites.

A probable parent body of the H chondrites (comprising about 46% of the ordinary chondrites) is 6 Hebe, but its spectrum is dissimilar due to what is likely a metal impact melt component.[3]

It is likely that the ordinary chondrites comprise a detailed sample of but a few select asteroids which happen to have been in the right place at the right time to send many fragments toward Earth at the present moment in solar system history. On the other hand, observations of 243 Ida by the Galileo spacecraft found weathering of Ida's surface, and the reflection spectra of freshly exposed parts of the surface resembled that of OC meteorites, while the older regions matched the spectra of common S-type asteroids.

Chemical composition

The ordinary chondrites comprise three mineralogically and chemically distinct groupings. They differ in the amount of total iron, of iron metal and iron oxide in the silicates:

  • The H chondrites have the Highest total iron, high metal, but lower iron oxide (Fa) in the silicates;
  • The L chondrites have Lower total iron, lower metal, but higher iron oxide (Fa) in the silicates;
  • The LL chondrites have Low total iron and Low metal, but the highest iron oxide content (Fa) in the silicates.

See also


  1. ^ Natural History Museum, meteorite catalogue
  2. ^ NASA (YouTube) – Dr. David Kring – Asteroid Initiative Workshop Cosmic Explorations Speakers Session
  3. ^ Gaffey, M. J.; Gilbert, S. L. (1998). "Asteroid 6 Hebe: The probable parent body of the H-Type ordinary chondrites and the IIE iron meteorites".  

External links

  • The Catalogue of Meteorites
  • A Pictorial of Ordinary Chondrites - Meteorites Australia
  • Gallery of Ordinary Chondrites by James St. John, a geologist at Ohio State University
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.