[meteorite-list] What are the top 10 most scientificallyimportant meteorites?

From: Jeff Grossman <jgrossman_at_meteoritecentral.com>
Date: Sun, 15 Feb 2009 07:53:00 -0500
Message-ID: <4998102C.5040003_at_usgs.gov>

[retransmit of message that didn't seem to go through]

I can speak to the subject of chondrites and what they tell us about the
very early solar system. I read the question in the present tense: what
ARE the most important meteorites [today].

Among ordinary chondrites, there is one meteorite that is clearly the
most important to current research: Semarkona. It is the least
metamorphosed ordinary chondrite and best preserves the pre-accretionary
record. NASA ADS lists >50 references that mention it in the abstract
since the year 2000. If you want to study primitive OCs, you study this
one if you can get it. Nothing else is close.

Among carbonaceous chondrites, there are several:

Acfer 094 has seen almost no thermal metamorphism and almost no aqueous
alteration, an extreme rarity among carbonaceous chondrites. It too is
a hotly studied meteorite. 50 references since 2000.

Murchison is still probably the king of CM chondrites. Although heavily
altered by water, none of the CMs have seen much heating, and they still
retain a good record of nebular and presolar processes. By virtue of
its large recovered mass, and the high content of organic compounds in
this group, it is still widely studied 40 years after the fall. >100
refs since 2000.

Although the CV chondrite Allende is now known to be fairly altered and
somewhat metamorphosed, no meteorite is studied as much, even today,
with >350 refs since 2000. It is especially important for what it tells
us about CAI formation. Another CV, Vigarano, also sees a lot of
research because it is less messed up than Allende (>50 refs since 2000)
and has a large mass in collections.

The fairly massive CI chondrite Orgueil is still the go-to meteorite in
this chemically primitive, unmetamorphosed, but greatly altered group,
especially for studies of organic compounds: >150 refs since 2000.

Other C chondrites like Renazzo, Isheyevo, and especially Tagish Lake
(>150 refs) are also widely studied. I think Kaidun is also a very
important meteorite due to the incredible diversity of clasts it
contains, but it is hard for researchers to obtain.

Among enstatite chondrites, it's harder to say which are the most
important. I guess I'd name Yamato 691 and Qingzhen as the most
important primitive ones. They are not widely studied these days.

So there are 12 of what I think are the most important chondrites. I
probably forgot some too!

Jeff

Sterling K. Webb wrote:
> Hi, Jason, List
>
> You're certainly right -- we are all interpreting the
> request quite differently. And yes, I am taking the
> "historical angle." But the point about history, particularly
> the history of an idea, is that certain objects or events
> do more than add to what we know; they make changes
> in how we think. We are able to think of meteorites AS
> meteorites because of L'Aigle. If some stone had not
> been recognized as a genuine proven rock that fell from
> the heavens, there would be no such thing as a meteorite.
>
> By that I mean, its physical reality aside, a meteorite
> is only a meteorite because we recognize it to be one;
> the categories of human knowledge are human constructs.
> No L'Aigle, no meteorites. Of course, I hope humanity is
> not so dense that L'Aigle was its only chance to figure
> it out. Maybe Pultusk would have been the "first" meteorite.
>
> The little enigimas you mention -- Graves Nunataks
> (GRA) 06128 and 06129, like NWA 011, Ibitira, Semarkona,
> Kaidun -- have unique stories, yes, some valuable, some
> still puzzles, and their full stories, when known, might be
> immensely important or just another footnote. They are
> the current mysteries whose importance is largely to show
> us we don't understand everything yet. Ten (or twenty) years
> from now, your list would be populated with new mysteries
> and new revelations (hopefully).
>
> The original criterion was "most significant in increasing
> our understanding of the evolution of our solar system."
> How far would our understanding of that go if we didn't
> know the Solar System was full of rocks? And weren't forced
> to the understanding that they were the leftovers? And
> therefore that the planets must have been cobbled together
> from them? And so forth.
>
> What would be the meteorites-yet-to-be-discovered that
> would be on that list? The first rock with unequivocal proof
> of life anywhere else than this little planet, at whatever time.
> That would go on my future list. The first rock found that
> did NOT originate in this solar system. It would make the
> list. Of course, these rocks may not exist...
>
> Personally, I think all the lists suggested to the List are
> good lists, just of thirteen (or 30 or 300) ways of looking
> at a blackbird (or a black rock).
>
>
>
> Sterling K. Webb
> ------------------------------------------------------------------------------
> ----- Original Message -----
> From: "Jason Utas" <meteoritekid at gmail.com>
> To: "Meteorite-list" <meteorite-list at meteoritecentral.com>
> Sent: Saturday, February 14, 2009 9:36 PM
> Subject: Re: [meteorite-list] What are the top 10 most
> scientificallyimportant meteorites?
>
>
> Hello Graham, Sterling, John, Jeff, Walter, Rob, All,
>
> With regards to Sterling's point - true enough, but that's taking the
> historical angle again - we didn't believe that impact craters
> existed, we find a crater surrounded by meteorites, and eventually
> enough research added up to prove that it was indeed an impact crater.
> But this could have been done at any other crater that wasn't badly
> eroded...it's like L'Aigle in the sense that you're talking about a
> paradigm shift that could have been caused by any meteorite, any
> crater. In fact, the meteorite itself in this case becomes irrelevant
> - you're talking about a crater being important, not the irons. And
> the irons are fairly typical IAB's, chemically very similar to a
> number of other irons.
>
> I think the trouble is that we need clarification when making such a
> list because, as a number of you are saying, we're all just making
> lists based on our interpretation of Graham's request. I saw his
> question as a demand for a list of meteorites which were of particular
> scientific note, and made just such a list - but even I became
> sidetracked in my mentioning of the first lunar and martian meteorites
> ever recognized, for they fall into the historically, rather than
> scientifically important category. Their discovery was of note, but
> the meteorites themselves...while not typical, they're nothing too out
> of the ordinary.
>
> So what determines whether or not a meteorite is of scientific
> interest? I believe that mentioning things like L'Aigle or Canyon
> Diablo in this case is wrong because the meteorites, while they did
> cause major shifts in how we see the solar system and how it works,
> are relatively ordinary. But beyond that...I believe Greg Hupe had a
> good point when he mentioned that there are a great number of
> meteorites that are of great scientific interest that are more or less
> ignored because they come from NWA. I think it's going to take
> looking beyond what we think of as rare, because what we know as
> collectors isn't really what's scientifically important. In many
> cases, we never get a chance to buy those rocks, and there's good
> reason for it.
>
> I see it in a number of the lists mentioned; at least one person
> mentioned Calcalong Creek - without even making note of ALHA81005, the
> first recognized lunar meteorite. Why? Calcalong Creek is a rare and
> beautiful meteorite, granted, but is it particularly scientifically
> important? No. But - it was the first lunar meteorite available to
> the public.
>
> Rocks like Graves Nunataks (GRA) 06128 and 06129, like NWA 011,
> Ibitira, Semarkona, Kaidun - they do much more individually to further
> our knowledge of the solar system. I couldn't make a list of ten,
> because saying which unique meteorite or trait of a particular
> meteorite holds greater importance isn't something I see as
> rewarding...thinking about it just makes me realize how fortunate we
> are to be able to actually collect and touch these pieces of the very
> distant past.
>
> Regards,
> Jason
>
> On Sat, Feb 14, 2009 at 7:03 PM, Sterling K. Webb
> <sterling_k_webb at sbcglobal.net> wrote:
>
>> Dear Jason, List,
>>
>>
>>> Canyon Diablo... helped us to understand impact dynamics
>>> but as to how that plays into our understanding of the
>>> evolution of the solar system...it doesn't, really.
>>>
>> Prior to the assertion that Meteor Crater was an impact
>> feature, the concept of "impact" as a possible event was
>> nil, non-existent, and when proposed was widely denied,
>> pooh-pooh'ed -- an affront to the orderly and rational
>> natural world.
>>
>> Barringer conceived of the crater as what we would call
>> a particularly large impact pit, not an explosive crater, but
>> the evidence drew him that way. Nininger was really the
>> first to understand the possibility of impact as a geological
>> process (without understanding the scale on which it was
>> possible) and that understanding led straight to the late Gene
>> Shoemaker, who single-handedly pushed a planet full of
>> resistant scientists into the realization by patiently rubbing
>> their noses in it for decades.
>>
>> Shoemaker's 1960 paper ending the 70-year dispute about
>> the origin of Meteor Crater caused a sensation in geology,
>> as it was the first definitive proof of an extraterrestrial impact
>> on the Earth's surface. This was the first crater "proved" to be
>> of impact origin. Proving that impact was a fundamental
>> geological process would take decades longer. Paradigms
>> don't always shift quickly.
>>
>> In the 1950's, the only cratered body known to science
>> was the Moon, so presumably craters were an odd or
>> unique feature in the Solar System, an individual characteristic
>> of the Moon, not of planetary bodies generally. It was virtually
>> universally understood that the 1000's of craters that covered
>> the Moon were volcanic features. Our exploration of the Moon
>> was substantially biased toward finding (mostly non-existent)
>> evidence of volcanic activity.
>>
>> Even the first photos of craters on Mars in 1965 by Mariner 4
>> did not budge that mindset much. This was one of those
>> you-had-to-be-there moments -- the shock and disbelief caused
>> by craters on Mars (and the quivers of denial that followed)
>> was profound, like being hit between the eyes with a two-by-four.
>> Well, they were probably volcanic craters anyway...
>>
>> The 1970's competed the change of paradigm and the fact of
>> impact as a geological process (the title of the book that nailed it
>> down firmly). That almost every body in the Solar System
>> with a solid surface is cratered is now a Ho Hum fact. The
>> reason that you, Jason, can think it's not important is because
>> you are on the "modern" side of the conceptual divide. Until
>> the understanding of impact, solar system formation models
>> were divided between "accretion" and "coalescence." Very
>> few people still believe planets formed like a dew drop any
>> more. The change in formation theory walks hand-in-hand
>> with impact theory.
>>
>> If Canyon Diablo was the catalyst for the recognition of
>> impact processes in the Solar System -- and I think it was --
>> then it might well be the "most significant in increasing our
>> understanding of the evolution of our solar system."
>>
>>
>> Sterling K. Webb
>> -----------------------------------------------------------------------------
>> ----- Original Message -----
>> From: "Jason Utas" <meteoritekid at gmail.com>
>> To: "Meteorite-list" <meteorite-list at meteoritecentral.com>
>> Sent: Saturday, February 14, 2009 5:08 PM
>> Subject: Re: [meteorite-list] What are the top 10 most
>> scientificallyimportant meteorites?
>>
>>
>> Hola All,
>> I would have to respectfully disagree. The original post my Graham
>> asked for a list of ten of "the most important meteorites with regard
>> to science," and he then went on to ask: "Which ones have been the
>> most significant in increasing our understanding of the evolution of
>> our solar system, and what they have taught us?"
>> I believe that the implication of his email was not to ask for a list
>> of meteorites that helped to further our acceptance of meteoritics as
>> a field, but rather to obtain a list of the ten most scientifically
>> interesting meteorites. And, to be perfectly frank, if L'Aigle had
>> been any other type (iron, stony-iron, etc), the outcome of the
>> situation would have been the same. As a meteorite, while it did help
>> to open our eyes as to what was actually out there, it did little to
>> tell us of the history of the formation of the solar system.
>> And Michael's list is more of a list of the most beautiful/interesting
>> meteorites from the point of view of a collector...it's just a
>> different sort of list. Did Esquel or Sylacouga contribute to our
>> knowledge about the early solar system? Not particularly, but they
>> are two of the more desireable meteorites around, for non-scientific
>> reasons. Canyon Diablo is interesting in its own right as a
>> crater-forming meteorite, as it helped us to understand impact
>> dynamics - but as to how that plays into our understanding of the
>> evolution of the solar system...it doesn't, really.
>> Regards,
>> Jason
>>
>>
>> On Sat, Feb 14, 2009 at 1:21 PM, Michael Blood <mlblood at cox.net> wrote:
>>
>>> Hi Jason and all,
>>> First of all, I think it should be mentioned that any such
>>> List is inevitably biased.
>>> Next, that said list cannot possibly "nail" a specific 10
>>> meteorites.
>>> Assuming these two prospects are accepted, here are 10
>>> Very respectable meteorites that would certainly merit full
>>> Consideration in comprising such a list ( and at least one "why"
>>> Per each:
>>>
>>> 1) Canyon Diablo:
>>> prototypical and stable iron from what was
>>> recognized as the "only" impact crater for a very long time. It
>>> Can be added that it was also the original site of the Nininger
>>> Museum
>>>
>>> 2) Allende: HUGE strewn field and, at the time, more than
>>> Doubled the total weight of known CR material available.
>>> It was also a witnessed fall with multiple hammer stones
>>> Striking homes and patios
>>>
>>> 3) Esquel: "The queen of the Pallasites" with fantastic color,
>>> Translucency, freedom from rust and in quantities large enough
>>> To allow any collector to have one of the few stable Pallasites.
>>>
>>> 4) Murchison: Providing most of the amino acids that comprise the
>>> "building blocks" of life, perhaps the most "studied" of any meteorite
>>> Ever and a major contributor to the angiosperm hypothesis. Again,
>>> a witnessed fall and a hammer.
>>>
>>> 5) Portalas Valley: Perhaps a surprise in many lists, this specimen has
>>> A unique physiology. Also a hammer.
>>>
>>> 6) Weston: The first scientifically recognized meteorite in "the new
>>> world."
>>> Also a hammer.
>>>
>>> 7. L'Aigle: see below. (Also, there will be a forthcoming article on the
>>> Status of L'Aigle as a hammer).
>>>
>>> 8) Ensischeim: "The meteorite from hell." (also a hammer if you care to
>>> consider a church courtyard a man made artifact). This is one of the
>>> richest
>>> events ever in the "lore" of meteorites.
>>>
>>> 9) Sikhote-Aline: producing thousands of what are pretty much agreed to
>>> be
>>> the world's most visually impressive iron individuals. Also a rare Iron
>>> witnessed fall.
>>>
>>> 10) Sylacauga: the only fully documented human striking meteorite.
>>>
>>> I could easily add several more, but these are just my 2 cents
>>> worth, anyway. I am likely wrong, as my wife repeatedly assures me
>>> I am.
>>> Best wishes, Michael
>>>
>>>
>>> On 2/14/09 4:59 AM, "Martin Altmann" <altmann at meteorite-martin.de> wrote:
>>>
>>>
>>>> Hi Jason,
>>>>
>>>> Even though we're living in a fast world and the "modernism" of our days
>>>> may
>>>> give the impression, that new scientific recoveries are drawn out of the
>>>> nothing.
>>>> But science and ideas are always integrated in traditions and contexts
>>>> and
>>>> are built on earlier steps.
>>>> Chladni hadn't invented the idea, that the stones may stem from outside.
>>>> He connected the idea that they come from space with the fireballs, the
>>>> existing stones and reports about the falls and postulated additionally,
>>>> that they could survive the atmospheric travel.
>>>> That approach was ridiculous for his contemporary scientists.
>>>> After the period of "enlightment" it was impossible that chunks fall
>>>> from
>>>> sky, Newton required empty spaces between the planets or at it best,
>>>> cause
>>>> they were Aristotelians, they had to be atmospheric products.
>>>> (Although Tycho had measured long before the parallaxes of comets, to
>>>> find
>>>> out that they move indeed in space).
>>>>
>>>> So Chladni's weird theory never would have been accepted, if there
>>>> wouldn't
>>>> have happened that proof, the mighty shower of L'Aigle, conveniently
>>>> close
>>>> to the Acad?mie de sciences.
>>>>
>>>> Therefore L'Aigle is for me a benchmark. Without L'Aigle no Chladni, no
>>>> Schreibers, no Daubr?e...no modern meteoritics. (At least not to the
>>>> advanced stage we have today).
>>>>
>>>> Shhht Jason, btw. Chladni isn't that much known as Father of
>>>> meteoritics,
>>>> but for his "Acoustics", he certainly is partially responsible for the
>>>> gig
>>>> tootling out from your speakers, while you're writing to the list :-)
>>>>
>>>> Sure it's only an ordinary chondrite, but you don't meet the meaning of
>>>> this
>>>> milestone, if you look with today's eyes on it.
>>>>
>>>>
>>>>> It's an ordinary chondrite, of which there are thousands
>>>>>
>>>> Which gives in fact to that class an especially high scientific
>>>> importance,
>>>> doesn't it? The chondrites conserved the most original information about
>>>> the
>>>> origin of our solar system, the processes who lead to the formation of
>>>> planets and they resemble much more the stuff we are all made from, than
>>>> any
>>>> differentiated meteorite, which tells us rather the history and
>>>> development
>>>> of his individual parent body. And ready we aren't yet with the
>>>> chondrites.
>>>> Ho many theories of chondrules genesis we have at present? Eleven?
>>>> Look the recent decade, the discovery of protoplanetary discs around
>>>> other
>>>> stars..... and so on.
>>>> Only because they are so readily available to the collectors and despite
>>>> the
>>>> antartcic ones so cheap like never before (yes Mrs.Caroline Smith.
>>>> Fletcher,
>>>> Hey, check the museum's archives, had to pay much more than you),
>>>> they shouldn't be disregarded.
>>>>
>>>> Hey, and confess Jason! The sight of something like that
>>>> http://www.chladnis-heirs.com/36.956g.jpg
>>>> doesn't it made your mouth water?
>>>>
>>>>
>>>> Well, each warehouse telescope for 30 bucks is better than that, which
>>>> Galilei pointed to the Moon or Jupiter. But what for an importance it
>>>> had!
>>>> Would we have a Hubble Space telescope now, without that use of the
>>>> lousy
>>>> lense 400 years ago? (Although maybe Galileo's or Copernicus' role is
>>>> maybe
>>>> sometimes somewhat overrated, media stars... Copernicus' system was in
>>>> practise inoperative and he had his Islamic and antique antecessors -
>>>> I'm
>>>> a
>>>> fan of Tycho, which was much more important for modern astronomy and our
>>>> view of the world, as he was the first, who trumped the Islamic
>>>> astronomy.
>>>> Without the results of his large-scale instruments, no Kepler, no
>>>> Newton,
>>>> no
>>>> Oberth, no Rovers on Mars, no security that the pieces in the Chladni
>>>> Boxes
>>>> really originated from the red planet...).
>>>> Of course it's never a continuously direct and mono-causal
>>>> development...
>>>> Chance and accident are also factors.
>>>> Allende and Murchison e.g. never would rank in the importance among the
>>>> first places, if they hadn't such large tkws or if they had fallen in
>>>> the
>>>> oceans and if there the Moon labs weren't just ready, when they felt.
>>>>
>>>> But in general L'Aigle was the proof.
>>>> Scientifically important, because with that fall, the concept of
>>>> meteorites
>>>> had to be accepted and the branch of this science was born at all.
>>>>
>>>> So it's my number one - only in my personal opinion of course.
>>>>
>>>> If we follow your criteria, Jason, everything but the very new had to be
>>>> ruled out and most probably we would have to make a ranking of the so
>>>> far
>>>> unique - the ungrouped and similar exotics, where we don't have fully
>>>> the
>>>> clues, what exactly it could be.
>>>>
>>>> Off now, have to jump into my carriage without horses.
>>>> (Hmmm was that important? Quite an unacceptable junk...
>>>> http://kuerzer.de/unimport
>>>> and we certainly would prefer a Lamborghini :-)
>>>>
>>>> Best!
>>>> Martin
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> -----Urspr?ngliche Nachricht-----
>>>> Von: meteorite-list-bounces at meteoritecentral.com
>>>> [mailto:meteorite-list-bounces at meteoritecentral.com] Im Auftrag von
>>>> Jason
>>>> Utas
>>>> Gesendet: Samstag, 14. Februar 2009 02:21
>>>> An: Meteorite-list
>>>> Betreff: Re: [meteorite-list] What are the top 10 most
>>>> scientificallyimportantmeteorites?
>>>>
>>>> Hola Martin,
>>>> I would have to disagree - when you go that far back, you wind up
>>>> dealing with meteorites that are of historic, rather than scientific
>>>> interest. L'Aigle may be something of an exception because it did
>>>> lead to the *scientific* acceptance of meteorites, but, from today's
>>>> scientific perspective, I wouldn't call it very important, never mind
>>>> giving it a place in the top ten. It's an ordinary chondrite, of
>>>> which there are thousands - it's no more special than, say, Tenham or
>>>> Gao - from a purely scientific point of view.
>>>> One might as well call the earliest fossils found the most important,
>>>> simply because they were found back in the day and led to our
>>>> recognition of what they really represented...while they may be
>>>> important, I would hesitate to call them extremely important from a
>>>> scientific point of view.
>>>> Regards,
>>>> Jason
>>>>
>>>> On Fri, Feb 13, 2009 at 5:12 PM, Martin Altmann
>>>> <altmann at meteorite-martin.de> wrote:
>>>>
>>>>> I choose L'Aigle as N?1.
>>>>>
>>>>> Cause else they wouldn't have recognized, that Chladni was right and
>>>>> that
>>>>> they are from space.
>>>>>
>>>>> Best!
>>>>> Martin
>>>>>
>>>>> -----Urspr?ngliche Nachricht-----
>>>>> Von: meteorite-list-bounces at meteoritecentral.com
>>>>> [mailto:meteorite-list-bounces at meteoritecentral.com] Im Auftrag von
>>>>> ensoramanda at ntlworld.com
>>>>> Gesendet: Samstag, 14. Februar 2009 00:55
>>>>> An: meteorite-list at meteoritecentral.com
>>>>> Betreff: [meteorite-list] What are the top 10 most scientifically
>>>>> importantmeteorites?
>>>>>
>>>>> Hi all,
>>>>>
>>>>> Just thought it might be interesting to discover list members opinions
>>>>> on
>>>>> what they would choose as the most important meteorites with regard to
>>>>> science? Which ones have been the most significant in increasing our
>>>>> understanding of the evolution of our solar system, and what they have
>>>>> taught us?
>>>>>
>>>>> Graham Ensor, UK.
>>>>> ______________________________________________
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>>>>>
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>>>>>
>>>>>
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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 Sun 15 Feb 2009 07:53:00 AM PST