[meteorite-list] Am I missing something here?
Alexander Seidel
gsac at gmx.net
Mon Jun 16 11:34:13 EDT 2008
Thank you, Jeff, for your quick reply. Seems that some type collectors will now feel a need to expand their meteorite inventories with the new subclasses, which is not an easy, or even impossible, task with almost all of those mentioned meteorites out of reach for a private person. So let´s hope some more exotic low-petrologic-type chondrites will surface in NWA or other hot deserts, as time goes by...
Alex
Berlin/Germany
[....whose Krymka had to step down a bit from the top of the ladder (sigh!) - yet remains a beauty!]
-------- Original-Nachricht --------
> Datum: Mon, 16 Jun 2008 10:50:53 -0400
> Von: Jeff Grossman <jgrossman at usgs.gov>
> An: "Alexander Seidel" <gsac at gmx.net>, meteorite-list at meteoritecentral.com, freequarks at gmail.com
> Betreff: Re: [meteorite-list] Am I missing something here?
> Yes. All of the low-petrologic-type chondrites can be refined. In
> Grossman and Brearley (2005) we reclassified Krymka as type 3.2 and
> Bishunpur as type 3.15. Here is the entire set of ordinary
> chondrite petrologic types from that paper:
>
> Semarkona -- 3.00
> QUE 97008 -- 3.05
> MET 00526 -- 3.05
> EET 90161 -- 3.05
> NWA 1756 -- 3.10
> NWA 3127 -- 3.10
> Roosevelt County 075 -- 3.10
> MET 96503 -- 3.10
> Adrar 003 -- 3.10
> Bishunpur -- 3.15
> Y-791324 -- 3.15
> Y-791558 -- 3.15
> Y-793596 -- 3.2
> Krymka -- 3.2
> GRO 95502 -- 3.2
> GRO 95544 -- 3.2
>
>
> jeff
>
> At 08:11 AM 6/16/2008, Alexander Seidel wrote:
> >Hi Jeff,
> >
> >if this is state of the art of the classification scheme, and has
> >been accepted by a majority of the meteoriticists, does this mean
> >some important primitive meteorites finally need a refinement of
> >their established classifications?
> >
> >I am thinking of (e. g.) the Krymka meteorite, which to my knowledge
> >is an LL3.1. Does this have to be refined to become either an
> >LL3.05, or an LL3.10, or an LL3.15 in the end?
> >
> >Just curious,
> >Alex
> >Berlin/Germany
> >
> >
> >-------- Original-Nachricht --------
> > > Datum: Mon, 16 Jun 2008 07:36:53 -0400
> > > Von: Jeff Grossman <jgrossman at usgs.gov>
> > > An: "Dark Matter" <freequarks at gmail.com>, "Meteorite List"
> > <meteorite-list at meteoritecentral.com>
> > > Betreff: Re: [meteorite-list] Am I missing something here?
> >
> > > Dear Martin and list,
> > >
> > > I can't comment on the CO3 oxymoron, but I am the inventor of the
> > > type 3.05 classification, so I can comment on that.
> > >
> > > As we have studied type 3 chondrites over the last 30 years,
> > > especially ordinary and CO chondrites, we have been gradually
> > > refining the 1967 Van Schmus and Wood classification scheme. In
> > > 1980, we realized that type 3 chondrites alone showed as great a
> > > range of metamorphic effects as type 4-6 did, so Sears and coworkers
> > > including me, proposed subdividing type 3 into types 3.0-3.9. In
> > > 2005, Grossman and Brearley (2005) described a similar wide range of
> > > metamorphic effects just between types 3.0 and 3.2 and subdivided
> > > this into 3.00-3.15 by steps of 0.05. Since then, we have even begun
> > > to recognize different levels of metamorphic heating between types
> > > 3.00 and 3.05, and so we find Acfer 094 at type 3.00, Semarkona at
> > > type 3.01, ALHA77307 at type 3.03 (e.g., Bonal et al. 2007; Kimura,
> > > Grossman and Weisberg, 2008, MAPS in press).
> > >
> > > These differences are quite real and important. In type 3.05
> > > ordinary chondrites, the olivine in chondrules has begun to decompose
> > > from its high-temperature state, the matrix chemistry is quite
> > > different, especially for sulfur, and the metal has greatly changed
> > > in structure and composition (all compared to the much, much rarer
> > > type 3.00-3.01 chondrites). Although these numbers do not tell you
> > > the peak metamorphic temperature, they are very useful in describing
> > > the various transitions that occur during metamorphic heating.
> > >
> > > The fact that there may be many possible combinations of chemical
> > > group and petrologic type is a good thing, although there certainly
> > > aren't 1500. Basically, current usage is 3.00-3.04 (5 categories),
> > > 3.05-3.15 (3 categories), 3.2-3.9 (8 catagories), 4-7 (4 categories)
> > > = 20 categories. I suppose if you double this for classifiers who
> > > can't make up their minds, you get ~40 categories, times 3 chondrite
> > > groups plus 2 transitional groups = ~200 total combinations.
> > >
> > > Jeff
> > >
> > > At 11:24 PM 6/15/2008, Dark Matter wrote:
> > > >Hi All,
> > > >
> > > >Twice in the past few days, I found myself staring at the screen in
> > > >confused disbelief. The two statements in sales ads:
> > > >
> > > >
> > > >"a yet unclassified CO3"
> > > >
> > > >and
> > > >
> > > >"absolutely rare type L3.05 !"
> > > >
> > > >just seem to me to border on absurdity. How can a unclassified
> > > >specimen be identified by its classification?
> > > >
> > > >And if we carry petrological grade to the hundredths, then
> > > >theoretically we could have over 1500 ordinary chondrite designations
> > > >not to mention all the transitional possibilities. I fail to see how
> > > >that level of hypothetical opinionated hair splitting could do any
> > > >good...except for ebay sales ads that is.
> > > >
> > > >Just an evening though when I should be working on something else.
> > > >
> > > >Cheers,
> > > >
> > > >Martin
> > > >______________________________________________
> > > >http://www.meteoritecentral.com
> > > >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
> > >
> > >
> > > ______________________________________________
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> > > 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
>
>
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