[meteorite-list] Anomalous and Ungrouped Ordinary Chondrites
Hello all, I've always been intrigued but puzzled about the classification of a few ordinary chondrites into the black hole of assigned classification names...ungrouped and/or anomalous. Some are specified with petrologic assignments and others without. Ebay on occasion offers us Hah 180 that is classified as an anomalous 3.5 ordinary chondrite and Dhofar 535 that is classified as ungrouped, and without a petrologic designation in its' description. According to David's site below...Hah 180 is similar to Deakin 001. And there maybe others I am not thinking of. Oxygen isotopes and weathering seem to be some of the key factors...and as stated on David's site they may come from a proximity close to where enstatite chondrites were formed, and in my opinion their appearance makes them at least look like some of the EL3's out there. Does anyone know what the latest theory is for these and will they one day get an official LL3 to 3.5 anomalous label which would finally give them a home? Seems to me to call them anything else puts them/keeps them in classification limbo. http://www.geocities.com/dgweir/HAH180.HTM Just curious, John __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
AW: [meteorite-list] Anomalous and Ungrouped Ordinary Chondrites
Hi John, and list, As to the ungrouped HaH 180, and Deakin 001, it has been suggested that both represent samples of a new and previously unsampled parent body. If that holds to be true, they will never get a LL or L classification. Ungrouped just means that a sample can't be assigned to any of the established groups, and that means also that they do most probably represent a unique parent body. Now, if we find three more meteorites like HaH 180, or Deakin 001, scientists will most likely create a new group, and then these samples won't be ungrouped, any longer. The term anomalous is used for meteorites that actually can be assigned to an existing group, but that differ in some aspects from the other known members of that group. Thus, HaH 180 isn't anomalous, it's simply ungrouped. Short: an ungrouped chondrite most probably stems from an asteroid that hasn't been sampled so far. An anomalous LL, for example, is most probably from the LL parent body/asteroid, but it differs from the other LL members in some respect. The petrologic grades have nothing to do with that, and of course an ungrouped chondrite can be a 3.5, or a plain 6. Hope this helps ;-) Best, Norbert A puzzled John wrote: Hello all, I've always been intrigued but puzzled about the classification of a few ordinary chondrites into the black hole of assigned classification names...ungrouped and/or anomalous. Some are specified with petrologic assignments and others without. Ebay on occasion offers us Hah 180 that is classified as an anomalous 3.5 ordinary chondrite and Dhofar 535 that is classified as ungrouped, and without a petrologic designation in its' description. According to David's site below...Hah 180 is similar to Deakin 001. And there maybe others I am not thinking of. Oxygen isotopes and weathering seem to be some of the key factors... and as stated on David's site they may come from a proximity close to where enstatite chondrites were formed, and in my opinion their appearance makes them at least look like some of the EL3's out there. Does anyone know what the latest theory is for these and will they one day get an official LL3 to 3.5 anomalous label which would finally give them a home? Seems to me to call them anything else puts them/keeps them in classification limbo. __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
Re: AW: [meteorite-list] Anomalous and Ungrouped Ordinary Chondrites
Norbert, Makes sense to me...it looks like some consistency is in order here. I wonder how many of these does Bernd have in an ungrouped listing, or has he gone ahead and grouped them in the LL's, etc. Are you out there Bernd??? What say? Do we have a good handle on which ones are ungrouped and related? How many samples does it take to create a new group? Is it when there is consistency in a few...if so, who would then come up with such a group? I know we have been down similar paths with the olivine diogenite naming and the like, but this part of classifications and group naming still seems very loose to me. John Hi John, and list, As to the ungrouped HaH 180, and Deakin 001, it has been suggested that both represent samples of a new and previously unsampled parent body. If that holds to be true, they will never get a LL or L classification. Ungrouped just means that a sample can't be assigned to any of the established groups, and that means also that they do most probably represent a unique parent body. Now, if we find three more meteorites like HaH 180, or Deakin 001, scientists will most likely create a new group, and then these samples won't be ungrouped, any longer. The term anomalous is used for meteorites that actually can be assigned to an existing group, but that differ in some aspects from the other known members of that group. Thus, HaH 180 isn't anomalous, it's simply ungrouped. Short: an ungrouped chondrite most probably stems from an asteroid that hasn't been sampled so far. An anomalous LL, for example, is most probably from the LL parent body/asteroid, but it differs from the other LL members in some respect. The petrologic grades have nothing to do with that, and of course an ungrouped chondrite can be a 3.5, or a plain 6. Hope this helps ;-) Best, Norbert A puzzled John wrote: Hello all, I've always been intrigued but puzzled about the classification of a few ordinary chondrites into the black hole of assigned classification names...ungrouped and/or anomalous. Some are specified with petrologic assignments and others without. Ebay on occasion offers us Hah 180 that is classified as an anomalous 3.5 ordinary chondrite and Dhofar 535 that is classified as ungrouped, and without a petrologic designation in its' description. According to David's site below...Hah 180 is similar to Deakin 001. And there maybe others I am not thinking of. Oxygen isotopes and weathering seem to be some of the key factors... and as stated on David's site they may come from a proximity close to where enstatite chondrites were formed, and in my opinion their appearance makes them at least look like some of the EL3's out there. Does anyone know what the latest theory is for these and will they one day get an official LL3 to 3.5 anomalous label which would finally give them a home? Seems to me to call them anything else puts them/keeps them in classification limbo. __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
Re: AW: [meteorite-list] Anomalous and Ungrouped Ordinary Chondrites
Norbert, I didn't read your comment very closely. It looks like you are saying it takes 5 samples to make a group. Where does that criteria come from? I know you are involved with the Society...so maybe there are known guidelines after all. thanx in advance. John Hi John, and list, As to the ungrouped HaH 180, and Deakin 001, it has been suggested that both represent samples of a new and previously unsampled parent body. If that holds to be true, they will never get a LL or L classification. Ungrouped just means that a sample can't be assigned to any of the established groups, and that means also that they do most probably represent a unique parent body. Now, if we find three more meteorites like HaH 180, or Deakin 001, scientists will most likely create a new group, and then these samples won't be ungrouped, any longer. The term anomalous is used for meteorites that actually can be assigned to an existing group, but that differ in some aspects from the other known members of that group. Thus, HaH 180 isn't anomalous, it's simply ungrouped. Short: an ungrouped chondrite most probably stems from an asteroid that hasn't been sampled so far. An anomalous LL, for example, is most probably from the LL parent body/asteroid, but it differs from the other LL members in some respect. The petrologic grades have nothing to do with that, and of course an ungrouped chondrite can be a 3.5, or a plain 6. Hope this helps ;-) Best, Norbert A puzzled John wrote: Hello all, I've always been intrigued but puzzled about the classification of a few ordinary chondrites into the black hole of assigned classification names...ungrouped and/or anomalous. Some are specified with petrologic assignments and others without. Ebay on occasion offers us Hah 180 that is classified as an anomalous 3.5 ordinary chondrite and Dhofar 535 that is classified as ungrouped, and without a petrologic designation in its' description. According to David's site below...Hah 180 is similar to Deakin 001. And there maybe others I am not thinking of. Oxygen isotopes and weathering seem to be some of the key factors... and as stated on David's site they may come from a proximity close to where enstatite chondrites were formed, and in my opinion their appearance makes them at least look like some of the EL3's out there. Does anyone know what the latest theory is for these and will they one day get an official LL3 to 3.5 anomalous label which would finally give them a home? Seems to me to call them anything else puts them/keeps them in classification limbo. __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
Re: AW: [meteorite-list] Anomalous and Ungrouped Ordinary Chondrites
Norbert stated the facts well about ungrouped and anomalous chondrites. There are no rules or guidelines for grouping meteorites. However, a lot of researchers subscribe to the idea, which I think originated with John Wasson, that it takes 5 to sufficiently define the properties of a bunch of related meteorites that a name could be proposed. The Editors of the Meteoritical Bulletin and the Catalogue of Meteorites probably wouldn't endorse a group-name if there were less than 5. Of course, there are researchers who really want to be the ones to coin new names, and they sometimes get a bit hasty. Anyway, for smaller sets of meteorites, the term grouplet is preferred by many, as is the suffix -like, each modifying the name of the best-known member. jeff At 11:19 PM 10/19/2003 +, [EMAIL PROTECTED] wrote: Norbert, I didn't read your comment very closely. It looks like you are saying it takes 5 samples to make a group. Where does that criteria come from? I know you are involved with the Society...so maybe there are known guidelines after all. thanx in advance. John Hi John, and list, As to the ungrouped HaH 180, and Deakin 001, it has been suggested that both represent samples of a new and previously unsampled parent body. If that holds to be true, they will never get a LL or L classification. Ungrouped just means that a sample can't be assigned to any of the established groups, and that means also that they do most probably represent a unique parent body. Now, if we find three more meteorites like HaH 180, or Deakin 001, scientists will most likely create a new group, and then these samples won't be ungrouped, any longer. The term anomalous is used for meteorites that actually can be assigned to an existing group, but that differ in some aspects from the other known members of that group. Thus, HaH 180 isn't anomalous, it's simply ungrouped. Short: an ungrouped chondrite most probably stems from an asteroid that hasn't been sampled so far. An anomalous LL, for example, is most probably from the LL parent body/asteroid, but it differs from the other LL members in some respect. The petrologic grades have nothing to do with that, and of course an ungrouped chondrite can be a 3.5, or a plain 6. Hope this helps ;-) Best, Norbert A puzzled John wrote: Hello all, I've always been intrigued but puzzled about the classification of a few ordinary chondrites into the black hole of assigned classification names...ungrouped and/or anomalous. Some are specified with petrologic assignments and others without. Ebay on occasion offers us Hah 180 that is classified as an anomalous 3.5 ordinary chondrite and Dhofar 535 that is classified as ungrouped, and without a petrologic designation in its' description. According to David's site below...Hah 180 is similar to Deakin 001. And there maybe others I am not thinking of. Oxygen isotopes and weathering seem to be some of the key factors... and as stated on David's site they may come from a proximity close to where enstatite chondrites were formed, and in my opinion their appearance makes them at least look like some of the EL3's out there. Does anyone know what the latest theory is for these and will they one day get an official LL3 to 3.5 anomalous label which would finally give them a home? Seems to me to call them anything else puts them/keeps them in classification limbo. __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.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 __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
