[meteorite-list] Sikhote crust-chondrite / Could this be one of the rarest meteorites found?

From: Jason Utas <meteoritekid_at_meteoritecentral.com>
Date: Wed, 18 Nov 2009 13:37:32 -0800
Message-ID: <93aaac890911181337l1f317e84xa6ccff092f0d193b_at_mail.gmail.com>

Carl, All,
Wow, thanks for that...hum.
Right - I think people are confusing rarity with desirability, market
value, and collector availability, when these are all really distinct
terms.
Right, it's all about O-isotopes now, but I'm not really sure why - it
seems to me that chemistry should be just as important...surely there
could have been parent bodies forming in the same general areas as
each other that were distinct bodies, but that, due to their relative
proximity, have similar or identical O-isotope values. I don't know -
maybe that is how we group things...seems illogical to me, though.

The trouble with "fusion crust..."
If I recall, a while back, Elton made some strange comments about a
fusion crust having to be composed of siliceous material and
impurities such as oxides etc. He argued that, because the crust that
forms on irons lacks silicates, it is not a true fusion crust.

The consensus of the list was that the crust that forms on irons may
be chemically distinct from the crust that forms on stones, but it is
for all intensive purposes analogous in pretty much every way to the
stony version, so we might as well call them the same thing.

I think the reason we don't see much in the way of fusion crust on
silicated irons is because, well, there aren't many fresh silicated
irons around. There are plenty of examples of crusted irons - and
with just over 50 iron falls, some of which are accessible to
collectors, well, they're there to be seen. I don't know how many of
those ~50 iron falls are silicated, but I do know one thing - of all
of them, Udei Station's the only one that's available in any real
quantity, and I've never seen an example with good crust. I don't
think that's because it didn't form a fusion crust - I just think that
such pieces aren't widely available, so they remain out of our field
of view, for the most part...

Think of Estherville, things like that. They're made of a pretty even
mix of iron and stone and they still form a fusion crust.

I have a ~4.7g 1/2 end of Bencubbin that shows some pretty spectacular
warty fusion crust...I can get some pictures up if you'd like. I
figure that's about 1/2 stone and metal as well, so...yeah.

Regards,
Jason

On Wed, Nov 18, 2009 at 10:26 AM, <cdtucson at cox.net> wrote:
> Jason, I would first like to say that if there were an award for most helpful and kind on this list you would be the winner.
> I truly believe you offer more good information than anyone else on this list. That says a lot because there are a ton of great people on this list. And I want to thank you for all you do. You are a tremendous person.
>
> I think you are 100% correct with this evaluation as you describe it. But, There is something to desirability / Valuable in the formula of "rare".
> Just because something is rare does not mean it is desirable or valuable. To me rarely is irrelevant if not desirable. As you correctly point out. Who cares about your L6. So, to me the rarest meteorite that has those things has got to be the meteorite that every collector wants the most.
> That said it would be a subjective call but for me it would be ALH 84001.
> Lastly, Your reference to Jeff Grossman are correct but I notice that Oxygen isotopes rule in this biz. If the air matches , then that is where it is from and therefore that is what it is.
> A recent example of this is GRA 06128. They are calling it a brachinite based on Isotopes even though it is not related in ?other ways to the brach clan. So, apparently the where it is from needs more specific categories like Mars now has four different categories.
> Anyway, I wanted to thank you for all your information. I know I had never seen actual fusion crust on any iron before yours. I have seen a lot of impostors but yours is truly the real deal.
> Has anyone ever studied that crust to determine what it is made up of? It seems from an earlier thread that the crust must be a mixture of the silicates within this meteorite. Because most other irons without silicates within them do not seem to leave a true fusion crust like your sikhote did? Thanks Carl
> --
> Carl or Debbie Esparza
> Meteoritemax
>
>
> ---- Jason Utas <meteoritekid at gmail.com> wrote:
>> Hello Sonny, All,
>> I've often thought about such a term - "the rarest meteorite."
>> The rarest meteorite would of course be smallest ungrouped meteorite,
>> for one could feasibly conceive of a 1-2g unique meteorite. ?When a
>> new type is named, however, a hype generally surrounds it - rather
>> like the olivine diogenite craze of a few years ago, or the confusion
>> surrounding Bencubbinites, and other poorly defined types of
>> meteorites.
>> The simple fact of the matter is that there meteorites are too often
>> categorized by our current system into associations and groups into
>> which they fit rather poorly; Jeff Grossman states as much in the last
>> thread surrounding the poor chemical and isotopic relationships
>> between many basaltic meteorites deemed "eucrites."
>> But regardless of this fact, a simple truth remains. ?There are
>> countless ungrouped meteorites and several Kakangari-type meteorites,
>> so while they may be one of the least common "types," they are by no
>> means examples of the "rarest" meteorite known.
>> Regards,
>> Jason
>>
>> On Tue, Nov 17, 2009 at 6:12 PM, ?<wahlperry at aol.com> wrote:
>> > Hi Bernd and list,
>> >
>> > ?Would this be one of the rarest meteorites ever found? If not, what
>> > meteorite would be?
>> >
>> > Thanks,
>> > Sonny
>> >
>> >
>> > -----Original Message-----
>> > From: bernd.pauli at paulinet.de
>> > To: Meteorite-list at meteoritecentral.com
>> > Sent: Tue, Nov 17, 2009 1:12 pm
>> > Subject: [meteorite-list] Photo of a K-chondrite
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > Hi Greg and List,
>> >
>> > Hardly any photos of Kakangaris exist. You'll find one on David
>> > Weir's excellent website: http://www.meteoritestudies.com/
>> >
>> > Click on chondrites and then scroll down to Kakangari!
>> >
>> > Thin section pics of Kakangari can be found here (on pages 202-205):
>> >
>> > D.S. LAURETTA, M. KILLGORE (2005) A Color Atlas of Meteorites in Thin
>> > Section
>> > (Golden Retriever Publications and Southwest Meteorite Press, ISBN
>> > 0-9720472-1-2, 301 pp.).
>> >
>> >
>> > Best wishes,
>> >
>> > Bernd
>> >
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>> >
>> >
>> >
>> >
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Received on Wed 18 Nov 2009 04:37:32 PM PST