[meteorite-list] Relict (fossil) meteorites

From: Matt Morgan <mmorgan_at_meteoritecentral.com>
Date: Sat, 06 Jan 2007 22:09:29 -0700
Message-ID: <45A08089.4010002_at_mhmeteorites.com>

To all who are interested in this:
In geology we use the term "weathered" or "altered" for rocks where the
*majority* of minerals have been replaced by a weathering product
(Fe-oxides, usually, in the case of chondritic meteorites). If the rock
is a real basket case we put the word "severely" in front of
"weathered". It seems to me that "relict" is sugar-coating the fact
that such meteorites are really severely weathered (W6) and have very
little (<5%) of the original mineralogy visible.

Perhaps the NomCom should add a W7 to Wlotzka's 1993 weathering grade
scheme to take care of the terminology issue.
Matt Morgan

David Weir wrote:

>
>Since the new category of relict (or fossil) meteorites was adopted by
>the Nomenclature Committee only this past October, I would imagine there
>are likely other relict meteorites in our collections which have not
>been so designated. The definition requires that more than 95% of a
>meteorite has been replaced by secondary phases since its fall. The
>meteorite Mills comes to mind as a possibility, but maybe its not quite
>there yet.
>
>David
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Received on Sun 07 Jan 2007 12:09:29 AM PST