Hi Pete,
Your statement that magnetite (Fe3O4) is one part wüstite (FeO) and
one part hematite (Fe2O3) is formally true (in terms of formula
adjustment) but not totally, regarding its physico-chemical properties
and especially its structure, that are different from what would
result in a mechanical admixture of wüstite and hematite.
Magnetite is actually a Fe(II) ferrate(III).
It should be written more correctly as Fe(Fe2O4) where the first iron
is a bivelent cation Fe(II) or Fe2+ that neutralizes an anion which is
(Fe2O4)2- and in which the 2 irons are Fe(III) or Fe3+
As Fe(II) is more electropositive than Fe(III), it preferably acts as
cation while Fe(III) ions would more readily be surrounded by enough
oxygens so as to build up an anion.
This being, I did not check whether the permeability of magnetite
results from that of wüstite or whether it is rather rearranged
otherwise, which should be far more likely in reagrd with the
completely different magnetite structural rearrangement.
Thanks you (and Greg) for your clear discrimination between
"magnetism" and "permeability", that really needed to be reminded.
More precisely, in electromagnetism, permeability is the measure of
the ability of a material to support the formation of a magnetic field
within itself. In other words, it is the degree of magnetization that
a material obtains in response to an applied magnetic field (info from
Wikipedia).
Happy New Year to all!
(In French we use to say "Bonne Année", meaning "Good New Year". But I
prefer by far the English wording. Indeed, it is not beacuse the year
is good that you'll necessarily be happy. It mostly depends on your
mental spirit and your intrinsic optimism. Some may be poor and/or ill
but still very happy.
I therefore wish everybody to acquire a very positive mantal spirit in
any circimstance, so far for this unpredictable 2012...)
Zelimir
--
Prof. Zelimir Gabelica
Université de Haute Alsace
ENSCMu, Lab. LPI-GSEC,
3, Rue A. Werner,
F-68093 Mulhouse Cedex, France
Tel: +33 (0)3 89 33 68 94
[email protected] a écrit :
Richard, the List.
There was a reply asking about magnetite.
Magnetite is a form of Iron oxide, having the
formula Fe3O2. The common chemical name is
ferrous-ferric oxide. The formula for magnetite
may also be written as FeO·Fe2O3, which is one part
wüstite (FeO) and one part hematite (Fe2O3).
It contains Iron, therefore it can be a
magnet because the iron has a high Permeability.
Alinco magnets were made before rare earth magnets.
They were made of a mixture of aluminium (Al), nickel (Ni)
and cobalt (Co) Sometimes copper and titanium were added.
In their day, these were the strongest magnets that were
available
Now I'm sure someone will pipe up and ask about
the rare earth magnets.
There are two types: neodymium magnets and samarium-cobalt magnets.
Neodymium magnets are made from an alloy of neodymium, iron and
boron: (Nd2Fe14B). These are the strongest of all the magnets.
Their only drawback is that they oxidize very eazy unless they
are covered with a corrosion protection layer of nichol or some other
material.
The other type of rare earth magnet is samarium-cobalt magnets.
The chemical formula is SmCo5,
These are made from samarium and cobalt.
These magnets are weaker than the neodymium magnets.
I hope this helps to clear up some of the confusion.
Pete Shugar
-------- Original Message --------
Subject: Re: [meteorite-list] Are_Mars_Meteorites_Magnetic?
From: <[email protected]>
Date: Thu, January 05, 2012 7:25 pm
To: "GREG LINDH" <[email protected]>, [email protected]
Cc: meteorite-list <[email protected]>
Hello list, Greg, Bernd,
Yes, everone uses the term magnetic but
that is not the proper word for what they
are trying to convey.
Greg, you are correct in your definition.
The correct term is Permeability.
Permeability is defined as the ability to be
attracted to a magnet.
Everything has Permeability, but it is to such
a small degree that the object will not stick to
the magnet. Almost all living things contain
some iron, which makes them have a slight Permeability.
There are only three metals with a high enough
Permeability to become a magnet. these are
iron, nichol, and colbalt. Some stainless steel
can have Permeability by deformation, that is, being
bent out of shape.
If you get bent out of shape, maybe you can be
attracted to a magnet. :)
A magnet attracts the iron because the iron has
Permeability.
Magnetic is the term meaning having the properties
of a magnet.
This is sorta like Meteroid, meteor, meteorite.
I'm sorry that I did not get this out sooner, but
life got in the way.
Pete Shugar
> -------- Original Message --------
> Subject: Re: [meteorite-list] Are Mars Meteorites Magnetic?
> From: GREG LINDH <[email protected]>
> Date: Tue, January 03, 2012 5:49 pm
> To: <[email protected]>
> Cc: meteorite-list <[email protected]>
>
>
> Hi Bernd,
>
> I meant to address this email to you and not to Eric. So here
it is again.
>
> I have always wondered why people here on the List, keep
referring to some meteorites as being "magnetic". To me, being
magnetic means having the properties of a magnet. There are no
meteorites that natually attract iron, so why are they described as
being "magnetic"? Am I wrong?
>
>
> Regards,
>
> Greg L.
>
>
>
>
>
> > From: [email protected]
> > To: [email protected]
> > Date: Tue, 3 Jan 2012 23:36:07 +0000
> > Subject: [meteorite-list] Are Mars Meteorites Magnetic?
> >
> > Eric inquired:
> >
> > "Are Mars meteorites magnetic at all?"
> >
> > Some of them are definitely attracted to a magnet!
> >
> > One of these is Bob Verish's Los Angeles and when I held
> > a magnet to one my LAs, it readily jumped to the magnet!
> >
> > See, for example:
> >
> > COLLINSON D.W.(1997) Magnetic properties of Martian meteorites:
> > Implications for an ancient Martian magnetic field (Meteoritics
32-6, 1997, 803).
> >
> > Best wishes for 2012,
> >
> > Bernd
> >
> >
> > ______________________________________________
> > HAPPY HOLIDAYS!!
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