What does 'meteorite classification' mean?

Meteorite classification is the systematic categorization of meteorites based on their mineralogical, chemical, and isotopic compositions, as well as their structural characteristics. This classification helps scientists understand the origins, history, and evolution of these extraterrestrial objects.

 

Meteorites are primarily divided into three main categories: stony, iron, and stony-iron.

 

  • Stony meteorites, the most common type, are further subdivided into chondrites and achondrites. Chondrites contain small, spherical particles called chondrules and are considered some of the oldest materials in the solar system. Achondrites lack chondrules and are often linked to differentiated planetary bodies.

 

  • Iron meteorites, composed mainly of metallic iron-nickel, are believed to originate from the cores of differentiated asteroids.

 

  • Stony-iron meteorites, such as pallasites and mesosiderites, contain roughly equal parts of metal and silicate minerals, offering insights into the boundary regions between an asteroid's core and mantle.

 

After visual identification has been determined as likely a meteorite, a specimen of 20g, or 20% when under 100g exists, is sent to a classifier at an institution that is approved as a repository for type-samples.

 

The classification process involves detailed laboratory analyses, including petrographic examination, electron microprobe analysis, and mass spectrometry. These techniques allow researchers to determine the mineral content, trace element distribution, and isotopic ratios, which are crucial for accurate classification.

 

After the laboratory processes are completed, meteorites are ascribed a name by a naming-committee called 'NomCom' (Nomenclature Committee). The classification is then submitted to the Meteoritical Society where it is reviewed in great detail.

 

The Meteoritical Society, a professional organization dedicated to the study of meteorites, maintains a comprehensive database of classified meteorites, The Meteoritical Bulletin (also known as the 'MetBul'), providing a valuable resource for researchers worldwide.

 

After a name is ascribed to a newly classified meteorite by NomCom, and accepted by the Meteoritical Society, it is published in the MetBul and can be considered fully classified and published. All classification data is available for everyone to see online in the database under the meteorite's name.

 

Understanding meteorite classification is essential for reconstructing the solar system's history and the processes that shaped planetary bodies. By studying meteorites, scientists can gain insights into the conditions present during the early solar system and the mechanisms of planetary differentiation and evolution. This knowledge not only enhances our understanding of Earth's formation but also informs the search for life beyond our planet.



Here is a link to the Meteoritical Bulletin (MetBull);

https://www.lpi.usra.edu/meteor/

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