[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interested in this: In geology we use the term "weathered" or "altered" for rocks where the *majority* of minerals have been replaced by a weathering product (Fe-oxides, usually, in the case of chondritic meteorites).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meteorite has been replaced by secondary phases since its fall.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 >______________________________________________ > >\ > > Received on Sun 07 Jan 2007 12:09:29 AM PST |
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