Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
Hi Jeff, I've been puzzled about what you said and perhaps I've misread or missed your comments. Why do you think the R chondrites should be included in the oc clan (rather than the carbonaceous)? I thought this was a very unique idea. Thank you all for this interesting topic. Carl Jeff Grossman wrote: I didn't say they ARE included in the OCs... I said that I thought they should be. As far as I know, I am alone in this opinion... and ...If we take a more expansive definition of ordinary chondrite than most of my rather conservative colleagues are normally willing to accept, I would say that the rarest group of OCs is the R chondrites (only ~100 are known and many of those are paired).In addition, a number of unique ungrouped meteorites are OC-like.But again, I don't know of any colleagues who agree with me that R chondrites are in the OC class. [I would say that the OC class has two clans, the H-L-LL clan and the R clan]. _ Hotmail: Powerful Free email with security by Microsoft. http://clk.atdmt.com/GBL/go/171222986/direct/01/ __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
*Sorry for the repost. My original question did not make much sense.* Hi Jeff, I've been puzzled about what you said and perhaps I've misread or missed your comments. Why do you think the R chondrites should be included in the oc clan? I thought this was a very unique idea. Thank you all for this interesting topic. Carl Jeff Grossman wrote: I didn't say they ARE included in the OCs... I said that I thought they should be. As far as I know, I am alone in this opinion... and ...If we take a more expansive definition of ordinary chondrite than most of my rather conservative colleagues are normally willing to accept, I would say that the rarest group of OCs is the R chondrites (only ~100 are known and many of those are paired).In addition, a number of unique ungrouped meteorites are OC-like.But again, I don't know of any colleagues who agree with me that R chondrites are in the OC class. [I would say that the OC class has two clans, the H-L-LL clan and the R clan]. _ Hotmail: Free, trusted and rich email service. http://clk.atdmt.com/GBL/go/171222984/direct/01/ __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
First off, be careful of the words clan and class. The way most of us use it, carbonaceous chondrites are a class, comprising many groups. Some C chondrite groups are associated into clans, like the CV-CK clan or the CM-CO clan. But not all people use the term clan, and those who do sometimes differ in which groups are in which clans. In any case, a clan is an association of groups that are thought to be related in some way, not necessarily originating on the same parent body. There are two major characteristics that separate ordinary from carbonaceous chondrites. 1) OCs are above the terrestrial fractionation line (TFL) for oxygen isotopes and CCs are below it (except for highly altered ones). 2) OCs are depleted in refractory lithophile elements and CCs either have solar abundances or above. (E chondrites are on the TFL and depleted in refractories.) R chondrites share these major properties with ordinary chondrites, and therefore are better lumped with the OCs. In fact, bulk composition and O isotopes are the key properties used to assign all the C chondrite groups to the carbonaceous class. I think it is reasonable to do the same with the R, H, L, and LL groups, that is, to assign them to a common class. We don't really have a name for this class, as ordinary chondrites have come to be synonymous with H-L-LL, which I would consider to be a clan of this unnamed class. I would NOT put R chondrites in the H-L-LL clan; they are in the same class. I guess part of the confusion is whether ordinary chondrites has to apply only to H-L-LL chondrites, or whether we can use this phrase as the name of an entire class. My initial preference was to do the latter. I said the ordinary chondrite class has two major clans, the H-L-LL clan and the R clan (which has but one member). On reflection, a more palatable solution would be to find a new name for this class, and then we could refer to the ordinary chondrite clan and the R chondrite clan within it. So, what do we call this class? You can't use noncarbonaceous chondrites because we also have the enstatite chondrites in their own class. I have no idea. Jeff Carl 's wrote: Hi Jeff, I've been puzzled about what you said and perhaps I've misread or missed your comments. Why do you think the R chondrites should be included in the oc clan (rather than the carbonaceous)? I thought this was a very unique idea. Thank you all for this interesting topic. Carl Jeff Grossman wrote: I didn't say they ARE included in the OCs... I said that I thought they should be. As far as I know, I am alone in this opinion... and ...If we take a more expansive definition of ordinary chondrite than most of my rather conservative colleagues are normally willing to accept, I would say that the rarest group of OCs is the R chondrites (only ~100 are known and many of those are paired).In addition, a number of unique ungrouped meteorites are OC-like.But again, I don't know of any colleagues who agree with me that R chondrites are in the OC class. [I would say that the OC class has two clans, the H-L-LL clan and the R clan]. _ Hotmail: Powerful Free email with security by Microsoft. http://clk.atdmt.com/GBL/go/171222986/direct/01/ __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@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 __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
Sorry for my poor use of terms. I really should be more careful. I've had to look up what refractory lithophile elements are: http://adsabs.harvard.edu/abs/1988mess.book..394L and terrestrial fractionation line (TFL): http://adsabs.harvard.edu/abs/2004AGUFM.V41D..08R Stuff like that flies over my head unless I look these things up. Now your explanations are a lot more clearer! :D Thanks Jeff! Carl PS: Is it just me or am I the only dumb guy on this list? _ Your E-mail and More On-the-Go. Get Windows Live Hotmail Free. http://clk.atdmt.com/GBL/go/171222985/direct/01/ __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
Hi Melanie and thanks for the enthusiasm you add to the list ... Here's a high to low sorting of the ordinary chondrites, for over 32,000 meteorites: 22.0% L6 (most common) 19.9% H5 12.9% L5 12.3% H4 11.5% H6 7.8% LL5 4.2% LL6 3.3% L4 2.2% H3 2.0% L3 0.8% LL4 0.8% LL3 0.1% L7 0.1% LL7 0.03% H7 (least common) But this common and rare is a misleading label. That is a harder question if you look too closely at the deails and consider inhomogeneous and brecciated ordinary chondrites. That can all become somewhat unique if you ask the right person. Then there are the motley crew of ungrouped ordinary chondrites where it is hard to generalize. Some may be a weak classification while others might truly be weird (rare). Just a few notes: the H7, L7, LL7 types are not widely used in the literature and border on impact melts, so I'd take them with a grain of salt unless someone goes postal on me in which case they are right in whatever they say. The way I listed these, the meteorites are counted by the lowest number and won't show up in the higher thermal (metamorphosed) levels. In other words, for example, an LL3.8-6 is counted with the LL3's. If you have a special meteorite, it can sometimes be a rarer type if you start to split hairs, like H3.8 instead of just grouping it within the H3's, but there is some degree of arbitrariness to this. The tendency is that more virgin Solar system stuff (closer and closer 3.00) is more special and like a holy grail (rare in a sense) to some who study that - since it is more representative of the original material before water and heat were added and did their thing. From hat we can try to get the proof we need to work out early formation processes and theorize on the related dynamics happening. By this logic, and considering it is a very studied meteorite, the precious meteorite SEMARKONA (LL3.00 or is it 3.01 :-)), a witnessed fall from India, is rather unique being the only one with that 3.00 classification, which makes it super intact since formation and especially interesting to experts, and most notably Dr. Jeff Grossman who reviewed and updated its classification upon careful study. By another measure, the common ordinary chondrite, L5, Canadian witnessed fall, VILNA, is one of those very few special meteorites that was imaged during atmospheric entry and a precise orbit was determined. It was not too far from Buzzard Coulee, and what makes it even more special is that it was classified from a (although witnesses heard pieces whizzing around) 94 milligram fragment with fusion crust. The only other specimen found was a 48 milligram piece! This becomes a wild anecdote of a meteorite tale when one considers that the bolide passed directly over the only camera recording the sky for 500 miles (over 800 km) and headed for the newly constructed and world's only UFO landing site which had been built for the Canadian Centennial exposition in St. Paul, Alberta, where it showered sparks (retro-rockets to some folks). In case you wondered, I believe the Japanese classified on Antarctic meteorite with 10 milligrams, if you can believe that! So what actually makes a meteorite rare can turn into a matter of semantics and who you ask. Even the scale of 3 to 6 (or 7) is somewhat arbitrary and just looks for convenient thermally changed cairns along the path toward melting. So if we went the other way, if H, L, and LL correspond to only three parent bodies, the frequency of the types follows: H 45.0% L 40.6% LL 14.3% Hope this helps a little with that general question! Kind wishes, Doug -Original Message- From: Melanie Matthews miss_meteor...@yahoo.ca To: meteorite-list@meteoritecentral.com Sent: Tue, Dec 15, 2009 7:01 am Subject: [meteorite-list] Ordinary chondrites - rarest to the most common classes G'mornin' listites,, What is the least common type of ordinary chondrite, as well as the most common? Thanks --- Melanie IMCA: 2975 eBay: metmel2775 Known on SkyRock Cafe as SpaceCollector09 Unclassified meteorites are like a box of chocolates... you never know what you're gonna get! __ Looking for the perfect gift? Give the gift of Flickr! http://www.flickr.com/gift/ __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
I agree with Doug... the rarest and most valuable type of OC from a scientific perspective is petrologic type 3.00-3.01, from any of the chemical groups. Only one is known... Semarkona. If we take a more expansive definition of ordinary chondrite than most of my rather conservative colleagues are normally willing to accept, I would say that the rarest group of OCs is the R chondrites (only ~100 are known and many of those are paired). In addition, a number of unique ungrouped meteorites are OC-like. But again, I don't know of any colleagues who agree with me that R chondrites are in the OC class. [I would say that the OC class has two clans, the H-L-LL clan and the R clan]. Jeff Mexicodoug wrote: Hi Melanie and thanks for the enthusiasm you add to the list ... Here's a high to low sorting of the ordinary chondrites, for over 32,000 meteorites: 22.0% L6 (most common) 19.9% H5 12.9% L5 12.3% H4 11.5% H6 7.8% LL5 4.2% LL6 3.3% L4 2.2% H3 2.0% L3 0.8% LL4 0.8% LL3 0.1% L7 0.1% LL7 0.03% H7 (least common) But this common and rare is a misleading label. That is a harder question if you look too closely at the deails and consider inhomogeneous and brecciated ordinary chondrites. That can all become somewhat unique if you ask the right person. Then there are the motley crew of ungrouped ordinary chondrites where it is hard to generalize. Some may be a weak classification while others might truly be weird (rare). Just a few notes: the H7, L7, LL7 types are not widely used in the literature and border on impact melts, so I'd take them with a grain of salt unless someone goes postal on me in which case they are right in whatever they say. The way I listed these, the meteorites are counted by the lowest number and won't show up in the higher thermal (metamorphosed) levels. In other words, for example, an LL3.8-6 is counted with the LL3's. If you have a special meteorite, it can sometimes be a rarer type if you start to split hairs, like H3.8 instead of just grouping it within the H3's, but there is some degree of arbitrariness to this. The tendency is that more virgin Solar system stuff (closer and closer 3.00) is more special and like a holy grail (rare in a sense) to some who study that - since it is more representative of the original material before water and heat were added and did their thing. From hat we can try to get the proof we need to work out early formation processes and theorize on the related dynamics happening. By this logic, and considering it is a very studied meteorite, the precious meteorite SEMARKONA (LL3.00 or is it 3.01 :-)), a witnessed fall from India, is rather unique being the only one with that 3.00 classification, which makes it super intact since formation and especially interesting to experts, and most notably Dr. Jeff Grossman who reviewed and updated its classification upon careful study. By another measure, the common ordinary chondrite, L5, Canadian witnessed fall, VILNA, is one of those very few special meteorites that was imaged during atmospheric entry and a precise orbit was determined. It was not too far from Buzzard Coulee, and what makes it even more special is that it was classified from a (although witnesses heard pieces whizzing around) 94 milligram fragment with fusion crust. The only other specimen found was a 48 milligram piece! This becomes a wild anecdote of a meteorite tale when one considers that the bolide passed directly over the only camera recording the sky for 500 miles (over 800 km) and headed for the newly constructed and world's only UFO landing site which had been built for the Canadian Centennial exposition in St. Paul, Alberta, where it showered sparks (retro-rockets to some folks). In case you wondered, I believe the Japanese classified on Antarctic meteorite with 10 milligrams, if you can believe that! So what actually makes a meteorite rare can turn into a matter of semantics and who you ask. Even the scale of 3 to 6 (or 7) is somewhat arbitrary and just looks for convenient thermally changed cairns along the path toward melting. So if we went the other way, if H, L, and LL correspond to only three parent bodies, the frequency of the types follows: H 45.0% L 40.6% LL 14.3% Hope this helps a little with that general question! Kind wishes, Doug -Original Message- From: Melanie Matthews miss_meteor...@yahoo.ca To: meteorite-list@meteoritecentral.com Sent: Tue, Dec 15, 2009 7:01 am Subject: [meteorite-list] Ordinary chondrites - rarest to the most common classes G'mornin' listites,, What is the least common type of ordinary chondrite, as well as the most common? Thanks --- Melanie IMCA: 2975 eBay: metmel2775 Known on SkyRock Cafe as SpaceCollector09 Unclassified meteorites are like a box of chocolates... you never know what you're gonna get! __ Looking for the perfect
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
Indeed, it's for the first time, that I read that R-chondrites are included in the OC-group. If so, why exactly them and not the K-chondrites, the Carbonaceous from grade 3-6, the ungrouped and the enstatite chondrites too? valuable type of OC from a scientific perspective is petrologic type 3.00-3.01 Where one has to say, that it's maybe too early to say that, Because the classification with decimal places, (even with two!), is a relatively new occurrence - most classifiers seems still to prefer to use a simple 3 - so that in case, there are still a lot known type-3ers awaiting to be revisited regarding the degree of their (un)equilibration. But I agree - Ordinary is a somewhat misleading term, - as the ordinary chondrites have told us most about the origin and formation of the solar system, the planets and ourselves, more than any iron or any lunar rock! Keep that always in mind, if you are tempted, now in the end of the desert-era and the decreed end of meteorite finding in so many countries, with all their weird and fancy exotic types, to wrinkle your nose about the ugly ordinary 25$-a-kilo-chunk from NWA-wonderland! Rare as brilliants they are - and they were our beginnings! Happy holidays to all! Martin -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Jeff Grossman Gesendet: Mittwoch, 16. Dezember 2009 11:33 An: Meteorite-list Betreff: Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes I agree with Doug... the rarest and most valuable type of OC from a scientific perspective is petrologic type 3.00-3.01, from any of the chemical groups. Only one is known... Semarkona. If we take a more expansive definition of ordinary chondrite than most of my rather conservative colleagues are normally willing to accept, I would say that the rarest group of OCs is the R chondrites (only ~100 are known and many of those are paired). In addition, a number of unique ungrouped meteorites are OC-like. But again, I don't know of any colleagues who agree with me that R chondrites are in the OC class. [I would say that the OC class has two clans, the H-L-LL clan and the R clan]. Jeff Mexicodoug wrote: Hi Melanie and thanks for the enthusiasm you add to the list ... Here's a high to low sorting of the ordinary chondrites, for over 32,000 meteorites: 22.0% L6 (most common) 19.9% H5 12.9% L5 12.3% H4 11.5% H6 7.8% LL5 4.2% LL6 3.3% L4 2.2% H3 2.0% L3 0.8% LL4 0.8% LL3 0.1% L7 0.1% LL7 0.03% H7 (least common) But this common and rare is a misleading label. That is a harder question if you look too closely at the deails and consider inhomogeneous and brecciated ordinary chondrites. That can all become somewhat unique if you ask the right person. Then there are the motley crew of ungrouped ordinary chondrites where it is hard to generalize. Some may be a weak classification while others might truly be weird (rare). Just a few notes: the H7, L7, LL7 types are not widely used in the literature and border on impact melts, so I'd take them with a grain of salt unless someone goes postal on me in which case they are right in whatever they say. The way I listed these, the meteorites are counted by the lowest number and won't show up in the higher thermal (metamorphosed) levels. In other words, for example, an LL3.8-6 is counted with the LL3's. If you have a special meteorite, it can sometimes be a rarer type if you start to split hairs, like H3.8 instead of just grouping it within the H3's, but there is some degree of arbitrariness to this. The tendency is that more virgin Solar system stuff (closer and closer 3.00) is more special and like a holy grail (rare in a sense) to some who study that - since it is more representative of the original material before water and heat were added and did their thing. From hat we can try to get the proof we need to work out early formation processes and theorize on the related dynamics happening. By this logic, and considering it is a very studied meteorite, the precious meteorite SEMARKONA (LL3.00 or is it 3.01 :-)), a witnessed fall from India, is rather unique being the only one with that 3.00 classification, which makes it super intact since formation and especially interesting to experts, and most notably Dr. Jeff Grossman who reviewed and updated its classification upon careful study. By another measure, the common ordinary chondrite, L5, Canadian witnessed fall, VILNA, is one of those very few special meteorites that was imaged during atmospheric entry and a precise orbit was determined. It was not too far from Buzzard Coulee, and what makes it even more special is that it was classified from a (although witnesses heard pieces whizzing around) 94 milligram fragment with fusion crust. The only other specimen found was a 48 milligram piece
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
At 09:27 AM 12/16/2009, Chladnis Heirs wrote: Indeed, it's for the first time, that I read that R-chondrites are included in the OC-group. If so, why exactly them and not the K-chondrites, the Carbonaceous from grade 3-6, the ungrouped and the enstatite chondrites too? I didn't say they ARE included in the OCs... I said that I thought they should be. As far as I know, I am alone in this opinion. There are only two Kakangari-like chondrites, and I am not prepared to put them anywhere. I'm not sure what the rest of the question means, but many ungrouped chondrites can be and are associated with a major class, as in ungrouped carbonaceous chondrite. jeff valuable type of OC from a scientific perspective is petrologic type 3.00-3.01 Where one has to say, that it's maybe too early to say that, Because the classification with decimal places, (even with two!), is a relatively new occurrence - most classifiers seems still to prefer to use a simple 3 - so that in case, there are still a lot known type-3ers awaiting to be revisited regarding the degree of their (un)equilibration. But I agree - Ordinary is a somewhat misleading term, - as the ordinary chondrites have told us most about the origin and formation of the solar system, the planets and ourselves, more than any iron or any lunar rock! Keep that always in mind, if you are tempted, now in the end of the desert-era and the decreed end of meteorite finding in so many countries, with all their weird and fancy exotic types, to wrinkle your nose about the ugly ordinary 25$-a-kilo-chunk from NWA-wonderland! Rare as brilliants they are - and they were our beginnings! Happy holidays to all! Martin -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Jeff Grossman Gesendet: Mittwoch, 16. Dezember 2009 11:33 An: Meteorite-list Betreff: Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes I agree with Doug... the rarest and most valuable type of OC from a scientific perspective is petrologic type 3.00-3.01, from any of the chemical groups. Only one is known... Semarkona. If we take a more expansive definition of ordinary chondrite than most of my rather conservative colleagues are normally willing to accept, I would say that the rarest group of OCs is the R chondrites (only ~100 are known and many of those are paired). In addition, a number of unique ungrouped meteorites are OC-like. But again, I don't know of any colleagues who agree with me that R chondrites are in the OC class. [I would say that the OC class has two clans, the H-L-LL clan and the R clan]. Jeff Mexicodoug wrote: Hi Melanie and thanks for the enthusiasm you add to the list ... Here's a high to low sorting of the ordinary chondrites, for over 32,000 meteorites: 22.0% L6 (most common) 19.9% H5 12.9% L5 12.3% H4 11.5% H6 7.8% LL5 4.2% LL6 3.3% L4 2.2% H3 2.0% L3 0.8% LL4 0.8% LL3 0.1% L7 0.1% LL7 0.03% H7 (least common) But this common and rare is a misleading label. That is a harder question if you look too closely at the deails and consider inhomogeneous and brecciated ordinary chondrites. That can all become somewhat unique if you ask the right person. Then there are the motley crew of ungrouped ordinary chondrites where it is hard to generalize. Some may be a weak classification while others might truly be weird (rare). Just a few notes: the H7, L7, LL7 types are not widely used in the literature and border on impact melts, so I'd take them with a grain of salt unless someone goes postal on me in which case they are right in whatever they say. The way I listed these, the meteorites are counted by the lowest number and won't show up in the higher thermal (metamorphosed) levels. In other words, for example, an LL3.8-6 is counted with the LL3's. If you have a special meteorite, it can sometimes be a rarer type if you start to split hairs, like H3.8 instead of just grouping it within the H3's, but there is some degree of arbitrariness to this. The tendency is that more virgin Solar system stuff (closer and closer 3.00) is more special and like a holy grail (rare in a sense) to some who study that - since it is more representative of the original material before water and heat were added and did their thing. From hat we can try to get the proof we need to work out early formation processes and theorize on the related dynamics happening. By this logic, and considering it is a very studied meteorite, the precious meteorite SEMARKONA (LL3.00 or is it 3.01 :-)), a witnessed fall from India, is rather unique being the only one with that 3.00 classification, which makes it super intact since formation and especially interesting to experts, and most notably Dr. Jeff Grossman who reviewed and updated its classification upon careful study. By another measure, the common ordinary chondrite, L5, Canadian
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
Get ready for NWA 5717. Initially anomalous, the classification had to be changed to ungrouped as it was too difficult to determine what it was anomalous to. 3.05 subtype. More to follow On Dec 16, 2009, at 10:26 AM, Jeff Grossman wrote: At 09:27 AM 12/16/2009, Chladnis Heirs wrote: Indeed, it's for the first time, that I read that R-chondrites are included in the OC-group. If so, why exactly them and not the K-chondrites, the Carbonaceous from grade 3-6, the ungrouped and the enstatite chondrites too? I didn't say they ARE included in the OCs... I said that I thought they should be. As far as I know, I am alone in this opinion. There are only two Kakangari-like chondrites, and I am not prepared to put them anywhere. I'm not sure what the rest of the question means, but many ungrouped chondrites can be and are associated with a major class, as in ungrouped carbonaceous chondrite. jeff valuable type of OC from a scientific perspective is petrologic type 3.00-3.01 Where one has to say, that it's maybe too early to say that, Because the classification with decimal places, (even with two!), is a relatively new occurrence - most classifiers seems still to prefer to use a simple 3 - so that in case, there are still a lot known type-3ers awaiting to be revisited regarding the degree of their (un)equilibration. But I agree - Ordinary is a somewhat misleading term, - as the ordinary chondrites have told us most about the origin and formation of the solar system, the planets and ourselves, more than any iron or any lunar rock! Keep that always in mind, if you are tempted, now in the end of the desert-era and the decreed end of meteorite finding in so many countries, with all their weird and fancy exotic types, to wrinkle your nose about the ugly ordinary 25$-a-kilo-chunk from NWA-wonderland! Rare as brilliants they are - and they were our beginnings! Happy holidays to all! Martin -Ursprüngliche Nachricht- Von: meteorite-list-boun...@meteoritecentral.com [mailto:meteorite-list-boun...@meteoritecentral.com] Im Auftrag von Jeff Grossman Gesendet: Mittwoch, 16. Dezember 2009 11:33 An: Meteorite-list Betreff: Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes I agree with Doug... the rarest and most valuable type of OC from a scientific perspective is petrologic type 3.00-3.01, from any of the chemical groups. Only one is known... Semarkona. If we take a more expansive definition of ordinary chondrite than most of my rather conservative colleagues are normally willing to accept, I would say that the rarest group of OCs is the R chondrites (only ~100 are known and many of those are paired). In addition, a number of unique ungrouped meteorites are OC-like. But again, I don't know of any colleagues who agree with me that R chondrites are in the OC class. [I would say that the OC class has two clans, the H-L-LL clan and the R clan]. Jeff Mexicodoug wrote: Hi Melanie and thanks for the enthusiasm you add to the list ... Here's a high to low sorting of the ordinary chondrites, for over 32,000 meteorites: 22.0% L6 (most common) 19.9% H5 12.9% L5 12.3% H4 11.5% H6 7.8% LL5 4.2% LL6 3.3% L4 2.2% H3 2.0% L3 0.8% LL4 0.8% LL3 0.1% L7 0.1% LL7 0.03% H7 (least common) But this common and rare is a misleading label. That is a harder question if you look too closely at the deails and consider inhomogeneous and brecciated ordinary chondrites. That can all become somewhat unique if you ask the right person. Then there are the motley crew of ungrouped ordinary chondrites where it is hard to generalize. Some may be a weak classification while others might truly be weird (rare). Just a few notes: the H7, L7, LL7 types are not widely used in the literature and border on impact melts, so I'd take them with a grain of salt unless someone goes postal on me in which case they are right in whatever they say. The way I listed these, the meteorites are counted by the lowest number and won't show up in the higher thermal (metamorphosed) levels. In other words, for example, an LL3.8-6 is counted with the LL3's. If you have a special meteorite, it can sometimes be a rarer type if you start to split hairs, like H3.8 instead of just grouping it within the H3's, but there is some degree of arbitrariness to this. The tendency is that more virgin Solar system stuff (closer and closer 3.00) is more special and like a holy grail (rare in a sense) to some who study that - since it is more representative of the original material before water and heat were added and did their thing. From hat we can try to get the proof we need to work out early formation processes and theorize on the related dynamics happening. By this logic, and considering it is a very studied meteorite, the precious meteorite SEMARKONA (LL3.00 or is it 3.01 :-)), a witnessed fall from
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
Martin wrote: Where one has to say, that it's maybe too early to say that, Because the classification with decimal places, (even with two!), is a relatively new occurrence... Dear Martin, Your comment sounds to me like the hungry man's dubitable evaluations of the quality of the the world's leading pancake expert, which persisted until he ate his fill of her goodies. Ref: The Perfect Pancake by Virginia Kahl http://tinyurl.com/ygjnju6 There are many parallels between say, beach combing and meteorite collecting. While beauty is in the eye of the beholder and a thousand and one contortions of the word rarity can and will be made by the interested, I would personally say there is tendency of beachcombers to want shells that are intact, whether it be for aesthetic reasons or scientific study to best figure out everything from the evolution to the habits of the mollusk who created his shell. The case is similar with meteorites. Jeff's comment (as did mine) referred to the scientific value of pristine examples which have not been cooked or watered down. That is undeniable for those interested in the question of genesis. Jeff and I have side-stepped the question of rarity. Personally I think it is moot here. If someone wants to study something else like an LL3/LL4 smash up, or all the power to them regarding rarity claims, since, like Semarkona LL3.00, only one of them appears in the database. Without considering Plutoing the R-chondrites, and with all respect that each meteorite is unique in its own way, here´s the overview on LL3 classification: LL's are the rarest of the H-L-LL tribe (representing only 14%), LL3 represents only 0.8% of OC's, the least frequent in the database. Petrological grade 3's of any type (H-L-LL) are also the rarest well-established classification - just 5%. That would make LL3 a natural regarding rarity, above and beyond its scientific desirability to leading researchers like Jeff. Again the words holy grail for OC's come to mind. The association of low petrological grade (3) with scarcity for recovered meteorites is only being extrapolated to the extreme with Semarkona, and is of very arguably special scientific value: Here´s the current LL3 situation in numbers: Type # %LL's LL3.X or LL3.XX 157 58.58% LL3 102 38.06% LL3-XX 8 2.99% LL3/4 1 0.37% To the point: As you can see, there is plenty more than a natural human inclination towards perfection (with respect to raw sampling of the unaltered first meteorites to condense from the soup) in the database to argue that a LL3.00 or LL3.01 is hard to to find. I´m hopeful you are right and more most primitive OC's are found as classification gets more complex, but the tendency that many will be is just not there if you look over the numbers so far covering (in this case) over half of all LL3's. If you want to say, for example, the rarest is the H7 classification - all nine of them- such as NWA 2898, I won't argue. Many scientists have purposefully avoided that classification which is another story. It just depends where your interests lie and all meteorites have their unique story. I don't think we can look at this as a bell curve with a 3 end and 7 end as the tails, though. If we hypothesize that there is an OC-type origin point I hope we are having a go at a singularity and elucidation of commonality In the Beginning... I know, most of us would rather remain on the fence eating all flavors of pancakes :-) ... it's such a loaded question ... Kind wishes, and happy holidays Doug -Original Message- From: Chladnis Heirs n...@chladnis-heirs.com To: Meteorite-list@meteoritecentral.com Sent: Wed, Dec 16, 2009 8:27 am Subject: Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes Indeed, it's for the first time, that I read that R-chondrites are included in the OC-group. If so, why exactly them and not the K-chondrites, the Carbonaceous from grade 3-6, the ungrouped and the enstatite chondrites too? valuable type of OC from a scientific perspective is petrologic type 3.00-3.01 Where one has to say, that it's maybe too early to say that, Because the classification with decimal places, (even with two!), is a relatively new occurrence - most classifiers seems still to prefer to use a simple 3 - so that in case, there are still a lot known type-3ers awaiting to be revisited regarding the degree of their (un)equilibration. But I agree - Ordinary is a somewhat misleading term, - as the ordinary chondrites have told us most about the origin and formation of the solar system, the planets and ourselves, more than any iron or any lunar rock! Keep that always in mind, if you are tempted, now in the end of the desert-era and the decreed end of meteorite finding in so many countries, with all their weird and fancy exotic types, to wrinkle your nose about the ugly ordinary 25$-a-kilo-chunk from NWA-wonderland! Rare as brilliants
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
Hi Doug, never I'd dare so. It was only an observation. In former times there weren't 3.05 etc and as you know, we frequently give type-3s in classification. Some classifier make decimal places, some not or not yet. Neither I had said something about the rareness. And I fully agree about the pleasure to take a bath in as pristine chondrules as thinkable. My observation was a simple quantifying one. No time, to harvest the database (I'm currently waiting to be on the road, but due blizzards roads in half of the country of my destination are closed). But I suppose, that half of the type-3s weren't checked yet more detailed, so that we can hope for more extremely unequilibrated ones! (Especially if you keep in mind, that there is almost no meteorite with name nor with an Antarctic number, which couldn't be rivalled by a hot desert find, concerning the sole material). Let it snow, let it snow, let it snow. (But not exactly now!!) Martin -Ursprüngliche Nachricht- Von: Mexicodoug [mailto:mexicod...@aim.com] Gesendet: Mittwoch, 16. Dezember 2009 18:01 An: n...@chladnis-heirs.com; Meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes Martin wrote: Where one has to say, that it's maybe too early to say that, Because the classification with decimal places, (even with two!), is a relatively new occurrence... Dear Martin, Your comment sounds to me like the hungry man's dubitable evaluations of the quality of the the world's leading pancake expert, which persisted until he ate his fill of her goodies. Ref: The Perfect Pancake by Virginia Kahl http://tinyurl.com/ygjnju6 There are many parallels between say, beach combing and meteorite collecting. While beauty is in the eye of the beholder and a thousand and one contortions of the word rarity can and will be made by the interested, I would personally say there is tendency of beachcombers to want shells that are intact, whether it be for aesthetic reasons or scientific study to best figure out everything from the evolution to the habits of the mollusk who created his shell. The case is similar with meteorites. Jeff's comment (as did mine) referred to the scientific value of pristine examples which have not been cooked or watered down. That is undeniable for those interested in the question of genesis. Jeff and I have side-stepped the question of rarity. Personally I think it is moot here. If someone wants to study something else like an LL3/LL4 smash up, or all the power to them regarding rarity claims, since, like Semarkona LL3.00, only one of them appears in the database. Without considering Plutoing the R-chondrites, and with all respect that each meteorite is unique in its own way, here´s the overview on LL3 classification: LL's are the rarest of the H-L-LL tribe (representing only 14%), LL3 represents only 0.8% of OC's, the least frequent in the database. Petrological grade 3's of any type (H-L-LL) are also the rarest well-established classification - just 5%. That would make LL3 a natural regarding rarity, above and beyond its scientific desirability to leading researchers like Jeff. Again the words holy grail for OC's come to mind. The association of low petrological grade (3) with scarcity for recovered meteorites is only being extrapolated to the extreme with Semarkona, and is of very arguably special scientific value: Here´s the current LL3 situation in numbers: Type # %LL's LL3.X or LL3.XX 157 58.58% LL3 102 38.06% LL3-XX 8 2.99% LL3/4 1 0.37% To the point: As you can see, there is plenty more than a natural human inclination towards perfection (with respect to raw sampling of the unaltered first meteorites to condense from the soup) in the database to argue that a LL3.00 or LL3.01 is hard to to find. I´m hopeful you are right and more most primitive OC's are found as classification gets more complex, but the tendency that many will be is just not there if you look over the numbers so far covering (in this case) over half of all LL3's. If you want to say, for example, the rarest is the H7 classification - all nine of them- such as NWA 2898, I won't argue. Many scientists have purposefully avoided that classification which is another story. It just depends where your interests lie and all meteorites have their unique story. I don't think we can look at this as a bell curve with a 3 end and 7 end as the tails, though. If we hypothesize that there is an OC-type origin point I hope we are having a go at a singularity and elucidation of commonality In the Beginning... I know, most of us would rather remain on the fence eating all flavors of pancakes :-) ... it's such a loaded question ... Kind wishes, and happy holidays Doug -Original Message- From: Chladnis Heirs n...@chladnis-heirs.com To: Meteorite-list@meteoritecentral.com Sent: Wed, Dec 16, 2009 8:27 am Subject: Re: [meteorite-list] Ordinary chondrites
Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes
Hello List, In keeping with the current discussion on uncommon common chondrites, I would like to announce that I have my first official classification underway. The paperwork has been submitted to the MS for a NWA number. The meteorite in question is the same small stone that I suspected was a CR2 type, and I posted some photos to the List asking for advice. Well, I sent a sample to UCLA for classification and the results are back. It is an LL3.6 chondrite. :) I will post more information about it when the classification is complete. Unfortunately for collectors, very little will be available on the open market. I am keeping a small slice, selling a tiny end cut, and the rest of the mass was donated to the UCLA collection for study. I'm at the hospital currently, so I don't have access to the photos stored on my own laptop. Best regards, MikeG On 12/16/09, Martin Altmann altm...@meteorite-martin.de wrote: Hi Doug, never I'd dare so. It was only an observation. In former times there weren't 3.05 etc and as you know, we frequently give type-3s in classification. Some classifier make decimal places, some not or not yet. Neither I had said something about the rareness. And I fully agree about the pleasure to take a bath in as pristine chondrules as thinkable. My observation was a simple quantifying one. No time, to harvest the database (I'm currently waiting to be on the road, but due blizzards roads in half of the country of my destination are closed). But I suppose, that half of the type-3s weren't checked yet more detailed, so that we can hope for more extremely unequilibrated ones! (Especially if you keep in mind, that there is almost no meteorite with name nor with an Antarctic number, which couldn't be rivalled by a hot desert find, concerning the sole material). Let it snow, let it snow, let it snow. (But not exactly now!!) Martin -Ursprüngliche Nachricht- Von: Mexicodoug [mailto:mexicod...@aim.com] Gesendet: Mittwoch, 16. Dezember 2009 18:01 An: n...@chladnis-heirs.com; Meteorite-list@meteoritecentral.com Betreff: Re: [meteorite-list] Ordinary chondrites - rarest to the most common classes Martin wrote: Where one has to say, that it's maybe too early to say that, Because the classification with decimal places, (even with two!), is a relatively new occurrence... Dear Martin, Your comment sounds to me like the hungry man's dubitable evaluations of the quality of the the world's leading pancake expert, which persisted until he ate his fill of her goodies. Ref: The Perfect Pancake by Virginia Kahl http://tinyurl.com/ygjnju6 There are many parallels between say, beach combing and meteorite collecting. While beauty is in the eye of the beholder and a thousand and one contortions of the word rarity can and will be made by the interested, I would personally say there is tendency of beachcombers to want shells that are intact, whether it be for aesthetic reasons or scientific study to best figure out everything from the evolution to the habits of the mollusk who created his shell. The case is similar with meteorites. Jeff's comment (as did mine) referred to the scientific value of pristine examples which have not been cooked or watered down. That is undeniable for those interested in the question of genesis. Jeff and I have side-stepped the question of rarity. Personally I think it is moot here. If someone wants to study something else like an LL3/LL4 smash up, or all the power to them regarding rarity claims, since, like Semarkona LL3.00, only one of them appears in the database. Without considering Plutoing the R-chondrites, and with all respect that each meteorite is unique in its own way, here´s the overview on LL3 classification: LL's are the rarest of the H-L-LL tribe (representing only 14%), LL3 represents only 0.8% of OC's, the least frequent in the database. Petrological grade 3's of any type (H-L-LL) are also the rarest well-established classification - just 5%. That would make LL3 a natural regarding rarity, above and beyond its scientific desirability to leading researchers like Jeff. Again the words holy grail for OC's come to mind. The association of low petrological grade (3) with scarcity for recovered meteorites is only being extrapolated to the extreme with Semarkona, and is of very arguably special scientific value: Here´s the current LL3 situation in numbers: Type # %LL's LL3.X or LL3.XX 157 58.58% LL3 102 38.06% LL3-XX 8 2.99% LL3/4 1 0.37% To the point: As you can see, there is plenty more than a natural human inclination towards perfection (with respect to raw sampling of the unaltered first meteorites to condense from the soup) in the database to argue that a LL3.00 or LL3.01 is hard to to find. I´m hopeful you are right and more most primitive OC's are found as classification gets more complex, but the tendency that many will be is just not there if you look over
[meteorite-list] Ordinary chondrites - rarest to the most common classes
G'mornin' listites,, What is the least common type of ordinary chondrite, as well as the most common? Thanks --- Melanie IMCA: 2975 eBay: metmel2775 Known on SkyRock Cafe as SpaceCollector09 Unclassified meteorites are like a box of chocolates... you never know what you're gonna get! __ Looking for the perfect gift? Give the gift of Flickr! http://www.flickr.com/gift/ __ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
