[meteorite-list] New Australian fall-Non Vesta Eucrite

From: Jeff Grossman <jgrossman_at_meteoritecentral.com>
Date: Fri, 18 Sep 2009 21:57:16 -0400
Message-ID: <4AB43A7C.20804_at_usgs.gov>

I don't think there's a difference between any of these meteorites in
terms of what we should call them. We just don't have consistent
terminology in place. Ibitira, NWA 011, and, it appears, Bunburra
Rockhole are all basaltic achondrites that seem to come from a separate
parent body than other basaltic achondrites. In my opinion, none of
these should be called a eucrite, just as we don't call angrites
eucrites. I would prefer to call them ungrouped basaltic achondrites.

If I had a peer-reviewed reference that handled the nomenclature well,
I'd change the recommended classifications in the MetBull database.

Jeff
Jason Utas wrote:
> Well, oxygen isotopes are one thing, but orbital data would seem to be
> a strange way to classify a meteorite to me; given the past four and a
> half billion years of collisions, things have been far too 'messed up'
> in the inner solar system for that to mean much; we have comets
> present in stable orbits here in the innrer solar system, and it
> doesn't mean that they formed there.
> And most would also make a clear definition between chemical and
> isotopic data, which he confuses (or the reference was a misquote) in
> the article.
> After all, Ibitira's a "Eucrite," but NWA 011's an ungrouped
> achondrite. It's the chemical difference that seems to make the
> difference in nomenclature.
> Jason
>
> On Fri, Sep 18, 2009 at 5:47 PM, Michael Fowler <mqfowler at mac.com> wrote:
>
>> Additional information from a Scientific American link that says that the
>> meteorite is not from Vesta, because the orbit is wrong, and the oxygen
>> isotopes are different.
>>
>>
>> http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=recovered-meteorite-points-to-an-un-2009-09-17
>>
>>
>> Mike Fowler
>> Chicago
>>
>>
>>
>>>> And I think it might be interesting to note this article, where Dr.
>>>> Philip Bland can be quoted as stating that Eucrites are not, in fact,
>>>> from Vesta.
>>>>
>>>> Go figure.
>>>>
>>>> http://au.news.yahoo.com/a/-/technology/6075299/rare-meteorite-found-in-outback/
>>>>
>>>> Regards,
>>>> Jason
>>>>
>>> Jason,
>>>
>>> You were a little bit hasty or misleading in your summarizing of Dr
>>> Bland.
>>>
>>> see quote below from the article you cited. (and to think that we are
>>> always criticizing reporters for getting it wrong!)
>>>
>>> Mike Fowler
>>> Chicago
>>>
>>>
>>>
>>> ""Dr Bland says most basalt meteorites, like the one found in the
>>> Nullarbor, originate from a large asteroid called Vesta but the
>>> Bunburra Rockhole meteorite is different.
>>>
>>> "Our little guy can't be from Vesta, the composition is all wrong," he
>>> said.""
>>>
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-- 
Dr. Jeffrey N. Grossman       phone: (703) 648-6184
US Geological Survey          fax:   (703) 648-6383
954 National Center
Reston, VA 20192, USA

Received on Fri 18 Sep 2009 09:57:16 PM PDT