[meteorite-list] Use of magnets for meteorite hunting

From: mafer <mafer_at_meteoritecentral.com>
Date: Thu Apr 22 10:23:45 2004
Message-ID: <022301c2e2bc$060f7300$6501a8c0_at_vs.shawcable.net>

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 <ROBERT.D.MATSON_at_saic.com>
To: 'rochette' <rochette_at_cerege.fr>; <meteorite-list@meteoritecentral.com>
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.
>
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Received on Tue 04 Mar 2003 09:07:18 PM PST