AW: WG: [meteorite-list] Classification question

From: Jeff Grossman <jgrossman_at_meteoritecentral.com>
Date: Thu May 13 07:02:04 2004
Message-ID: <5.1.0.14.2.20040513065212.03611bd0_at_gsvaresm05.er.usgs.gov>

Not gonna happen. The types-1 and -2 designations are archaic, even for
carbonaceous chondrites. The problem is that some type 3's are aqueously
altered and some type 2's are thermally metamorphosed. This is what
happens when you use one digit to signify two variables. Since the type
3.0-6 scale is well defined and the numbers mean something in terms of a
metamorphic sequence and the type-2 category is just descriptive and
nonquantitative, it would be a step in the wrong direction to start
dropping 3.x in favor of 2.

jeff

> > BTW: A petrologic type 2 has never been assigned to any ordinary
> chondrite. Only to carbonaceous chondrites.
> >
> > J?rn
>
>Hi J?rn,
>
>It was proposed in a paper I read a while back that Semarkona may be
>consistent with a petrographic type 2 classification due to aqueous
>alteration. I guess it's possible.
>
>David
>______________________________________________
>Meteorite-list mailing list
>Meteorite-list_at_meteoritecentral.com
>http://six.pairlist.net/mailman/listinfo/meteorite-list

Dr. Jeffrey N. Grossman phone: (703) 648-6184
US Geological Survey fax: (703) 648-6383
954 National Center
Reston, VA 20192, USA
Received on Thu 13 May 2004 07:01:23 AM PDT