[meteorite-list] Magnetic suscptibility of the chondrules

From: PAOLO CONTE <progetto.andromeda_at_meteoritecentral.com>
Date: Sat, 10 Jun 2017 20:07:05 +0200
Message-ID: <CAM55BZLaoEJLNVPr7sHnpg3mrbMXh0wh9G0DP9MtAyM7O4iD7g_at_mail.gmail.com>

Hello Listers,

I have a question for you. We know the ordinary chondrites and some
carbonaceous chondrites are attracted more or less sensibly by a magnet
because they contain iron.

The amount of iron is very variable: 19-22% in the case of LL chondrites of
the total weight of the sample, up to 25-30% in the case of H chondrites.

Part of this iron is chemically combined with other elements to form the
rock minerals of the matrices and of the chondrules, but another part of
iron is present as "free metal" in the form of metal grains in the matrices
(15-19% of the weight of the sample for H chondrites and 0,3-3% only for LL
chondrites).

Until a few months ago I was convinced that the free iron in the matrices
was the only one responsible for the magnetic attraction.

But now I am no longer sure after I have discovered that the loose
chondrules of Saratov meteorite (L4) are noticeably attracted by a small
neodymium magnet.

It is not easy to have loose chondrules, especially from classified
chondrites. I made tests (in addition to Saratov) with some loose
chondrules of NWA 10669 (LL3) too.

Most of NWA 10669 chondrules are inert, only someone responds weakly, but
only with very powerful neodimium magnets. A person could say: this is
normal, because Saratov is an L chondrite and NWA 10669 is a LL.
However, recently,
a French collector of meteorites confirmed to me the chondrules of
Bjurb?le (L/LL4) are very reactive in the presence of a magnet. Please,
note that Bjurb?le is a L/LL.

We know the condrules contain minerals with combined iron, *but sometimes
also **metallic <https://en.wikipedia.org/wiki/Metal> Fe-Ni*. Therefore, does
the magnetic susceptibility of the chondrules depend on this metallic Fe-Ni?
*But is this metallic Fe-Ni enough to produce magnetic susceptibility of
the chondrules? *Is there a scientific paper regarding the amount of
metallic Fe-Ni in the chondrules of several classified chondrites?

I have spoken about these tests with my compatriot Francesco Moser (IMCA
#1510), who advances another interesting hypothesis: the magnetic
susceptibility of chondrules of Saratov may depend (also) on free iron
micrograins in the matrix remaining attached to the surface of the
chondrules. What do you think about it? I cannot exclude this interesting
hypothesis.

If you have loose chondrules, please, make some tests and let me know athe
results of your experiments. Unfortunately, I own few loose chondrules from
Saratov and NWA 10669 and none from other classified meteorites. And,
sincerely, I don't want to broken my pieces to make other tests.

Thanks in advance to all the Listers who want help me to understand this
intriguing question.

Best regards from Rome, Italy

Paolo Conte
IMCA #6037
Meteoritical Society #6262
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Received on Sat 10 Jun 2017 02:07:05 PM PDT