Meteorite Monday: Carbonaceous Chondrites

This post marks the first of, what I’m hoping to be many, a weekly series about various meteorites. I love space rocks as much as I love their terrestrial cousins because they recount the history of our solar system. In the simplest of terms meteorites are basically chunks of natural space debris (i.e., not from man made objects) that survived their descent through the earths atmosphere and the resulting collision. These objects come primarily from asteroids such as Vesta 4, but a few have been found of lunar and martian origin.

Allende, Mexico Carbonaceous Chondrite

Allende, Mexico Carbonaceous Chondrite

A carbonaceous chondrite is basically a big ball of space mud  that can contain up to 20% water (I’m not remembering where I read that, so that number may change when I find the source). They are fairly soft and don’t survive their sojourn on the earth to well. These chondrites also represent the most primitive matter drifting through the solar system and have undergone the least amount of  chemical and physical change when compared to ordinary chondrites. It’s estimated that they represent roughly 5% of the meteorites that are observed and collected upon entry to the atmosphere (1).

The Orgueil Meteorite

The Orgueil Meteorite from the Hoover study

As of last month a carbonaceous chondrite found itself in the center of a controversy when a NASA astrobiologist, Richard Hoover, declared that he found fossilized bacteria in a specimen discovered in the late 1800’s. I won’t go into his claims here because this isn’t  a biology blog and I don’t have the expertise to handle such a topic. If you’re really interested you can click here and read the abstract. Also a quick google search will bring up all the arguments for and against Hoover’s claims.

  1. Bischoff, A.; Geiger, T. (1995). “Meteorites for the Sahara: Find locations, shock classification, degree of weathering and pairing”. Meteoritics 30 (1): 113–122.