[meteorite-list] Relict (fossil) meteorites

[Matt Morgan]

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*majority* of minerals have been replaced by a weathering product 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meteorite has been replaced by secondary  phases since its fall.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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