[meteorite-list] More data

From: mexicodoug <mexicodoug_at_meteoritecentral.com>
Date: Mon, 3 Dec 2007 11:34:04 -0600
Message-ID: <00f301c835d2$b4438fb0$4001a8c0_at_MICASA>

Hi Pete and welcome to the meteorite world online!

"Also, the heat of the entry into the atmosphere will kill any magnetism of
the meteorite"

This wouldn't usually be expected to be true - and though this would be more
likely for an iron meteorite, other fine structures (and even volatiles) are
preserved in the interiors of meteorites due to continuous ablation which
sweats off the heat extremely efficiently. Remember most stone meteorites
in reliable reports of immediate recovery are cold to touch. So we can
generally rule out stone meteorites as having been initially magnetized. A
better argument to rule out irons is: how would it be magnetized in the
first place, considering the formation was in a hot, melted core which very
slowly cooled off - slower than anything on Earth's surface can do?

A secondary argument, is, will magnetic properties persist after 4.5 billion
years of gradual relaxation in the metals (and formation of Widmanstatten
bands)? Is there a source in the Solar system capable of magnetization? I
bet you can aswer those well...

"the shock of the material being ejected from the parent body will also kill
the magnetism"

Heat is not always a destroyer of magnetization. In a laboratory example of
a piece of iron you can demonstrate this, but, some materials might be
heated and will actually ferromagnetize by crystalization (when quenched in
some cases for example), when before that had formed randomly oriented (on a
micro scale). I would suggest that impact could also cause magnetization
for selected materials under the right conditions, but couldn't back this up
off-hand. Generally in an impact, not all materials are shocked equally
like by your sledgehammer over an anvil. In collisions in space, we have
seen all sorts of shock levels as well as material that may be basically
unshocked.

Best wishes
Doug


----- Original Message -----
From: "Peter A Shugar" <pshugar at clearwire.net>
To: <Meteorite-list at meteoritecentral.com>
Sent: Monday, December 03, 2007 10:56 AM
Subject: [meteorite-list] More data


> Mike,
> Consider this. When the meteorite or iron comes into the magnetic field
> of the magnet, it is attracted
> to the magnet. This could be construed as the first stroke of the piece on
> the magnet. The piece needs to be stroked in the same direction a number
> of times to become a magnet, so with only the "one" stroke,
> it would leave the piece very slightly magnetic !!
> Magnetite is a naturally occurring mineral that is already magnetic. It's
> attracted to the magnet,and the orientation of the magnetite will be such
> that its polarity is the opposite of the pole on the magnet.
> As to the 'slightly magnetic" meteorite, remember the above, it's the
> first "stroke".
> Also, the heat of the entry into the atmosphere will kill any magnetism of
> the meteorite.
> Lastly, the shock of the material being ejected from the parent body will
> also kill the magnetism.
> This can be demonstrated by simply taking a magnet and bashing it very ,
> very hard with a sledge hammer.
> The one blow may not kill all the magnetism, but it surely will be a
> weaker magnet.
> This causes the aligned molecules of the magnet to be scrambled, thus
> destroying the magnet.
> Naturally occurring magnetic meteorite----No.
> Pete
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Received on Mon 03 Dec 2007 12:34:04 PM PST