Meteorite Monday: Ordinary Chondrites

Before I move too far into this post I should define two important terms so that we’re all on the same page:

  • Chondrite- basically the sedimentary rock of the solar system. It’s an aggregate of the left over material from the formation of the solar system.
  • Chondrule- Kind of the vagabonds of the proto solar system. They started off as molten spheres of either pyroxene, olivine or another silicate mineral that glommed onto the nearest asteroid, cooled and became the round features so prominent in ordinary chondrites.

If you have further questions (or even corrections/critiques) post it in the comments and I’ll do my best to address it.

The term “ordinary chondrite” is a bit misleading. Rocks that formed during or even before the formation of the solar system are anything but ordinary. Rather, they are the most commonly found meteorite on the earth. Their stony composition makes them more resilient than their carbonaceous brethren and as such, there is a ton of material about them that one can study. I don’t want to get into the details in this post because I need a little more time to study it and do the topic justice. However, I will list the three classes of ordinary chondrites (from Wikipedia):

  1. H Chondrites- Highest total iron, high metal, but lower iron oxide in the silicates
  2. L Chondrites- Lower iron total AND metal content, but higher iron oxide in the silicates
  3. LL Chondrites- Low iron total and low metal content, but higher yet in iron oxides

So basically, what separates the three classes is the iron and iron oxide content. As one goes up the other goes down.


Ordinary Chondrite Northwest Africa 1756

Ordinary Chondrite Northwest Africa 1756- image from Northern Arizona University

Those round blobs in this image are the chondrules. In a later post I’ll give more information about this particular chondrite.

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8 thoughts on “Meteorite Monday: Ordinary Chondrites

  1. I remember when I had Geology classes I studied three types of meteorite (just the basis: the name and iron content), and “our” meteorites had interesting names, such as “aerolitos” and “siderolitos”. Does these names look familiar to you?

    Although my memory might fail, I think aerolites had a relatively low iron content, which makes me wonder if aerolite is another designation for LL Chondrites, or we’re speaking about totally different things?

    • I’m assuming that “siderolitos” translates to siderite, which is an iron carbonate mineral (FeCO3) and a type of iron meteorite. It’s not a meteorite I’m familiar with yet, but I do plan on writing about it in the future after I’ve studied up on it.

      I’m not sure what the aerolite would be, but if it’s low iron chances are it’s an LL or L chondrite. I did a google search on aerolite and came up with a company from Tuscon, Arizona that sells meteorites. Maybe the aerolite wasn’t the type, but the company it came from?

      • No, no, I’ve seen it too.
        I searched for aerolite (in a quick translation) and got the same results. But when I searched for “aerólitos” (the Portuguese word) I got several pages that treat them as meteorites, as I’ve learnt.

        By the way, in wikipedia’s page about aerólitos, it is said that they can be classified as chondrites or achondrite, I don’t know if this can help you.

      • I don’t believe you can classify chondrites and achondrites under the term aerolito. Chondrites haven’t undergone any melting or differentiation and contain chondrules. Achondrites on the other hand are basically space basalt. They’ve undergone some sort of melting and do not contain chondrules. I’m curious to see that link though. Can you post it in this comment section?

    • From what I understood, it looks like aerolito might be a common classification for the two types. I could be wrong, but I don’t think the term is based on a chemical classification. I only say that because of the lack of chondrites in the achondrite and the melting experienced by the achondrite.

      • Err.. that’s possible xD

        What I know about meteorites is restricted to their classification as siderolites, aerolites and siderites.

      • In all honesty I could be wrong about the classification. Meteorites nomeclature is a complicated procedure and I’ve barely scratched the surface on the subject in my readings. Thanks for bringing it to my attention though. I do enjoy the conversations!

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