Re: [meteorite-list] Use of magnets for meteorite hunting
Pierre, > Unfortunately every Saharan or Omani SNC has been tested with a magnet and > therefore are definitively useless to investigate further this issue. > Every is almost the correct word. Almost is the correct word. When I hunt with my mates, I do not use a magnet. Some of them does even if I ask not to use magnets. Only the more experienced do not use magnet; it is just a matter of time. Just a short story, from the field: we encountered a strewn field, obviously of the same fall. Some of us used magnets on their first finds. After a short brief, they put the magnets in thier pockets. The crust colour and regmaglypts more or less marked on the bigger individuals made them confident in the cosmicity of the rocks they where gatering. But then I have no control on magnetic fields during transportation. Packed in metallic travel cases and air shipped from Africa to Europe. We shoudl talke about it. My two cents, ( hey Euro has cents too !) Best regards Michel. > > Pierre > > > > __ > 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: [meteorite-list] Use of magnets for meteorite hunting
rob says: > >P.S. Perhaps a compass can be used as a "weaning" device? >It generates a minimal magnetic field, and yet is sensitive >enough to detect most H- and L-chondrites. > yes compass is able to detect (by a small deviation from N when you approach the stone) the magnetization of a say L or H. But it is tricky. The problem is that the effect is quite different in the natural state and on a piece that has already been submitted to high field (touching with a magnet or lightning stroke). For example a LL after magnet exposure make a larger deviation on the compass than a H in its natural state and then: >> It can easily discriminate between LL and L, L and H or even eucrite >> and howardite, for example. > >Ahhh, but what about weathering? If you can't see into the interior >of a meteorite, you'll know nothing about its weathering grade. The >range of responses corresponding to the various weathering grades of >an H (for instance) will easily intersect that of the L's and probably >even unweathered LL's. Presumably similar difficulties will be >encountered with achondrites. --Rob Right again (but I was told that efficient communication should convey only one message per time!). So lesson 2 is: a strongly (W2-3) weathered H is as magnetic as a fresh L then Mark says: >Hi Robert and list > >I'm curious about this latent magnetic field. If its anything like that used >for paleomag, of what real interest is it except that the meteorite came >from a body large enough to develope a magnetic field which, if my >understanding of magnetics is fair enough would only tell you the body >developed a field. And this may be debatable if there was enough heat around >the area where the meteorite came from that the field isn't "set in stone" >because of a major impact or something ripped the parent body apart (as may >be the case with irons and mesosiderites and such). If the rock is still >plastic when this occurs, the field is subject to many other factors and may >not even represent the parent body's field anyway. >Mark There are instances where this paleomagnetic signal is of high interest, but of course it's very complicated and a lot of meteorites are rather dumb in this field. But taking the example of martians, the paleomagnetic signal of SNC has triggered many scientific publications (among which 3 in Science I guess) discussing for example the low temperature transfer of ALH84001 from Mars to Earth and thus the possibility that Earth may have already been contaminated by martian bugs in the past (see e.g.: http://www.spaceref.com/Directory/Astrobiology_and_Life_Science/panspermia/, ver y controversial, I warn you!). Unfortunately every Saharan or Omani SNC has been tested with a magnet and therefore are definitively useless to investigate further this issue. Pierre __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Use of magnets for meteorite hunting
Hi Robert and list I'm curious about this latent magnetic field. If its anything like that used for paleomag, of what real interest is it except that the meteorite came from a body large enough to develope a magnetic field which, if my understanding of magnetics is fair enough would only tell you the body developed a field. And this may be debatable if there was enough heat around the area where the meteorite came from that the field isn't "set in stone" because of a major impact or something ripped the parent body apart (as may be the case with irons and mesosiderites and such). If the rock is still plastic when this occurs, the field is subject to many other factors and may not even represent the parent body's field anyway. Mark - Original Message - From: Matson, Robert <[EMAIL PROTECTED]> To: 'rochette' <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Tuesday, March 04, 2003 10:41 AM Subject: [meteorite-list] Use of magnets for meteorite hunting > Hi Pierre and List, > > Here's my take on the use of magnets to search for meteorites. > If you're a novice meteorite hunter -- by all means use them! > Hobbling a beginner by removing this basic tool from his > arsenal is unfair, unrealistic, and completely unnecessary. > It's hard enough making that first find -- doing so without > a magnet will just make it take that much longer. > > As for disturbing the latent magnetic field of some ordinary > chondrite, the reality is that no one is ever going to spend > the money to measure it for your meteorite. No one. The > evidence? There are hundreds of thousands if not millions of > recovered meteorites in the world's collections today. On a > percentage basis, what fraction of those were found without > the use of a magnet (well over 95%) and what fraction of those > have been analyzed magnetically (less than 0.1%)? The point > I'm trying to make is that anyone really interested in the > latent magnetic fields of meteorites has far more material > already at their disposal than they could ever have time or > money to test. > > That said, I do not believe a magnet is especially useful > to a veteran meteorite hunter (who isn't searching a known > strewnfield). Indeed, as Pierre and others have argued, > dependence on a positive magnet response may eliminate > some of the rarer and more scientifically valuable > specimens. I still carry one with me, but I rarely use > it any longer. My eyes are a better discriminator. > > So to me it really boils down to a non-issue. When meteorite > hunters are first starting out, they'll use a magnet until > they have a few dozen ordinary chondrite finds. Sure, they'll > magnetically "kill" these finds, but their mounting success > will eventually wean them from their magnets at about the > time that over-dependence on them would hurt hunters more > than help them. --Rob > > P.S. Perhaps a compass can be used as a "weaning" device? > It generates a minimal magnetic field, and yet is sensitive > enough to detect most H- and L-chondrites. > > __ > 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: [meteorite-list] Use of magnets for meteorite hunting
Hello Mark and List, That is where a good metal detector comes in! Thanks, Tom The proudest member of the IMCA 6168 - Original Message - From: mafer <[EMAIL PROTECTED]> To: Tom aka James Knudson <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Tuesday, March 04, 2003 6:57 PM Subject: Re: [meteorite-list] Use of magnets for meteorite hunting > Hi Tom and list > But what about those that are covered by surface soil deposited by wind and > water after the fall? > I, too, have not been in a known strewn field, but it seems to me that with > the santa ana's of southern Cal, rocks could both be covered and uncovered > many times over the years. > > Mark > - Original Message - > From: Tom aka James Knudson <[EMAIL PROTECTED]> > To: Rafael B. Torres <[EMAIL PROTECTED]>; > <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; > <[EMAIL PROTECTED]> > Sent: Tuesday, March 04, 2003 3:02 PM > Subject: Re: [meteorite-list] Use of magnets for meteorite hunting > > > > Hello List, It seems to me, a beginner, that you can use a magnet to find > > the first meteorite then all the searching in the area should be done > > without one. After the first find you would know what you are looking for. > > Then if it turns out to be a strewn field they can test one of the others > > for all the magnetic stuff? If your first find turns out to be the only > one, > > Bummer! I personally like a magnet just because I am to lazy to keep > bending > > over and picking up rocks! ( not to mention the pain in the back by the > end > > of the hunt) > > > > Thanks, Tom > > The proudest member of the IMCA 6168 > > - Original Message ----- > > From: Rafael B. Torres <[EMAIL PROTECTED]> > > To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; > > <[EMAIL PROTECTED]> > > Sent: Tuesday, March 04, 2003 3:32 PM > > Subject: Re: [meteorite-list] Use of magnets for meteorite hunting > > > > > > > Hello Robert, I truly agree with you, right now I dont have 1,800 > dollars > > > for a magnet, instead I could use that money for meteorite training, > thus > > > harming the magnetic field history of the first meteorites, but after > that > > I > > > would be able to have more non-harmed meteorites. Even with magnets > > > meteorite searching is difficult for starters like me, so I think I > first > > > need some field training and then I can do it only with my eyes. I think > I > > > have now a good plan for a meteorite expedition, THANKS TO ALL THOSE > > PEOPLE > > > WHO HAVE HELPED ME..thanks a lot Michael¡... =0) > > > > > > > > > > > > =0) > > > Rafael B. Torres > > > Space Collection 2001 > > > http://www.geocities.com/rafael_blando > > > > > > > > > > > > _ > > > The new MSN 8: smart spam protection and 2 months FREE* > > > http://join.msn.com/?page=features/junkmail > > > > > > > > > __ > > > 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 > > > > > > > > __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Use of magnets for meteorite hunting
Hi Tom and list But what about those that are covered by surface soil deposited by wind and water after the fall? I, too, have not been in a known strewn field, but it seems to me that with the santa ana's of southern Cal, rocks could both be covered and uncovered many times over the years. Mark - Original Message - From: Tom aka James Knudson <[EMAIL PROTECTED]> To: Rafael B. Torres <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Tuesday, March 04, 2003 3:02 PM Subject: Re: [meteorite-list] Use of magnets for meteorite hunting > Hello List, It seems to me, a beginner, that you can use a magnet to find > the first meteorite then all the searching in the area should be done > without one. After the first find you would know what you are looking for. > Then if it turns out to be a strewn field they can test one of the others > for all the magnetic stuff? If your first find turns out to be the only one, > Bummer! I personally like a magnet just because I am to lazy to keep bending > over and picking up rocks! ( not to mention the pain in the back by the end > of the hunt) > > Thanks, Tom > The proudest member of the IMCA 6168 > - Original Message - > From: Rafael B. Torres <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; > <[EMAIL PROTECTED]> > Sent: Tuesday, March 04, 2003 3:32 PM > Subject: Re: [meteorite-list] Use of magnets for meteorite hunting > > > > Hello Robert, I truly agree with you, right now I dont have 1,800 dollars > > for a magnet, instead I could use that money for meteorite training, thus > > harming the magnetic field history of the first meteorites, but after that > I > > would be able to have more non-harmed meteorites. Even with magnets > > meteorite searching is difficult for starters like me, so I think I first > > need some field training and then I can do it only with my eyes. I think I > > have now a good plan for a meteorite expedition, THANKS TO ALL THOSE > PEOPLE > > WHO HAVE HELPED ME..thanks a lot Michael¡... =0) > > > > > > > > =0) > > Rafael B. Torres > > Space Collection 2001 > > http://www.geocities.com/rafael_blando > > > > > > > > _ > > The new MSN 8: smart spam protection and 2 months FREE* > > http://join.msn.com/?page=features/junkmail > > > > > > __ > > 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 > > __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Use of magnets for meteorite hunting
Hello List, It seems to me, a beginner, that you can use a magnet to find the first meteorite then all the searching in the area should be done without one. After the first find you would know what you are looking for. Then if it turns out to be a strewn field they can test one of the others for all the magnetic stuff? If your first find turns out to be the only one, Bummer! I personally like a magnet just because I am to lazy to keep bending over and picking up rocks! ( not to mention the pain in the back by the end of the hunt) Thanks, Tom The proudest member of the IMCA 6168 - Original Message - From: Rafael B. Torres <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Tuesday, March 04, 2003 3:32 PM Subject: Re: [meteorite-list] Use of magnets for meteorite hunting > Hello Robert, I truly agree with you, right now I dont have 1,800 dollars > for a magnet, instead I could use that money for meteorite training, thus > harming the magnetic field history of the first meteorites, but after that I > would be able to have more non-harmed meteorites. Even with magnets > meteorite searching is difficult for starters like me, so I think I first > need some field training and then I can do it only with my eyes. I think I > have now a good plan for a meteorite expedition, THANKS TO ALL THOSE PEOPLE > WHO HAVE HELPED ME..thanks a lot Michael¡... =0) > > > > =0) > Rafael B. Torres > Space Collection 2001 > http://www.geocities.com/rafael_blando > > > > _ > The new MSN 8: smart spam protection and 2 months FREE* > http://join.msn.com/?page=features/junkmail > > > __ > 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: [meteorite-list] Use of magnets for meteorite hunting
Hello Robert, I truly agree with you, right now I dont have 1,800 dollars for a magnet, instead I could use that money for meteorite training, thus harming the magnetic field history of the first meteorites, but after that I would be able to have more non-harmed meteorites. Even with magnets meteorite searching is difficult for starters like me, so I think I first need some field training and then I can do it only with my eyes. I think I have now a good plan for a meteorite expedition, THANKS TO ALL THOSE PEOPLE WHO HAVE HELPED ME..thanks a lot Michael¡... =0) =0) Rafael B. Torres Space Collection 2001 http://www.geocities.com/rafael_blando _ The new MSN 8: smart spam protection and 2 months FREE* http://join.msn.com/?page=features/junkmail __ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
