[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" <meteorite...@gmail.com>To: "Meteorite-list" <meteorite-list@meteoritecentral.com> Sent: Saturday, February 14, 2009 9:36 PMSubject: 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_w...@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" <meteorite...@gmail.com> To: "Meteorite-list" <meteorite-list@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 <mlbl...@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 bethe 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" <altm...@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 fromsky, 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 Académie de sciences. Therefore L'Aigle is for me a benchmark. Without L'Aigle no Chladni, no Schreibers, no Daubrée...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 thousandsWhich 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 lousylense 400 years ago? (Although maybe Galileo's or Copernicus' role is maybe sometimes somewhat overrated, media stars... Copernicus' system was inpractise inoperative and he had his Islamic and antique antecessors - I'ma 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 thefirst places, if they hadn't such large tkws or if they had fallen in theoceans 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 beruled 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 theclues, 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 -----Ursprüngliche Nachricht----- Von: meteorite-list-boun...@meteoritecentral.com[mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von JasonUtas 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 <altm...@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 -----Ursprüngliche Nachricht----- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von ensorama...@ntlworld.com Gesendet: Samstag, 14. Februar 2009 00:55 An: meteorite-list@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? 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