[meteorite-list] Classification of Chondrites

From: Rhett Bourland <rbourlan_at_meteoritecentral.com>
Date: Thu Apr 22 09:50:24 2004
Message-ID: <IOEBKAHMGFBDJMOFGDFNIEKNDIAA.rbourlan_at_evansville.net>

Thinking about this just a little bit more, the idea that 4's would have
equilibriated pyroxene but not olivine where as 5's would have equilibriated
pyroxene and olivine makes sense when you think about Bowen's Reaction
Series and the temperatures needed to metamorphose the various ingredients
of chondrites.
Bowen says that the first mineral to solidify from a magma is olivine
followed later by pyroxene. Knowing that, you can deduce that the last
mineral to be affected by a heating process would be olivine. I know that
type 3's are supposed to be from the surface of the parent body and the more
towards the center you go the higher the type (4-6) gets. Its generally
accepted that the deeper in the asteroid you go the warmer it gets. Why am
I talking about this stuff? The asteroid gets somewhat warm towards the
surface. Warm enough to equilibriate the pyroxene but not the olivine.
Move a little more towards the core, it gets a little warmer. Warm enough
to equilibriate both the pyroxene and the olivine.
Again, I don't really know how 6's would fit into this scheme of things and
I whole heartedly welcome any comments, good or bad, about what I've said.
Come on everyone, put your thinking caps on. Here's a chance for healthy
debate actually about meteorites and not about the normal things we argue
about on here.
Any and all comments are welcome and encouraged!!!
Rhett Bourland

-----Original Message-----
From: meteorite-list-admin_at_meteoritecentral.com
[mailto:meteorite-list-admin_at_meteoritecentral.com]On Behalf Of Michael
Sent: Sunday, April 07, 2002 8:01 PM
To: Bernd Pauli HD
Cc: Fred Olsen; meteorite-list
Subject: [meteorite-list] Classification of Chondrites

Bernd Pauli HD wrote:
> Slight correction: Cole Creek is an H5 chondrite. So far,
> so good (or bad). We discussed this about 18 months ago
> and when I got my Cole Creek thin section from Michael
> Blood, I got almost drowned in a sea of chondrules. But it
> does have a fayalite content (another important parameter)
> of 18.5 and this makes it clearly an H chondrite although
> not necessarily an H5 chondrite :-(
> Best wishes,
> Bernd
> ______________________________________________
Hi Bernd, Fred & all,
        It has always amazed me that Cole Creek is classified as a
5. I understand the "H" classification - but not the "5" - can
you, Bernd, or, anyone, tell us why a meteorite with such
clearly distinct and well defined (as well as colorful) chondrules
can be a "5?" (I REALLY wanna know...)
        Thanks, Michael

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Received on Sun 07 Apr 2002 09:49:51 PM PDT

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