[meteorite-list] Sweaty Fingers, Chlorides, and Chondrites

[Adam Hupe]

Hi Stephen and List,

I found the best way to preserve chondrites when cut is the following:

If the specimen comes with a lacquer coating remove it immediately as it
only serves to trap moisture inside the specimen.

Polish it to the highest degree possible.  If under polished it will attract
moisture because of a greater surface area.  If over polished you will
sometimes lose contrast.  Both sides should be polished immediately after
cutting to reduce the surface area that tends to trap moisture.  Every
meteorite is different so you have to continue to monitor the specimen
throughout the process.

Never cut or polish a meteorite using tap water because the chlorine
combines with water later on and will slowly disintegrate the piece.  After
polishing the specimen clean it using 99.9% pure ethyl alcohol in a
hypersonic cleaner.  Remove it from the bath and wipe it immediately with a
lint free cloth.  Then slowly heat the specimen to drive off any remaining
liquids.  We use an infrared heat lamp with air circulating around the
specimen to drive off excess moisture. We take the specimen up to 150
degrees Fahrenheit for 40 minutes and then cool it down slowly.  If the
alcohol is left to air dry it has a tendency to attract water so it should
always be heated.

And finally, store the specimen in an environment where the temperature does
not change rapidly.  More than 12 degrees per hour temperature changes have
detrimental long term affects.  I store most specimens at room temperature
with air circulating to prevent condensation which is a real problem in
Washington state.

Hope this helps,

------------------------------------
Adam Hupe
The Hupe Collection
Team LunarRock
IMCA 2185
raremeteorites at comcast.net




----- Original Message ----- 
From: "Jörn Koblitz" <koblitz at microfab.de>
To: "Stephen McMann" <stephen_mcmann at hotmail.com>;
<meteorite-list at meteoritecentral.com>
Sent: Monday, December 20, 2004 9:41 AM
Subject: AW: [meteorite-list] Sweaty Fingers, Chlorides, and Chondrites


Dear Stephen,

Thank you for your interesting (and important) questions, regarding
preservation of chondrites (or more general: stony meteorites). I try to
answer them from a scientific point of view:

> 1.  Can one easily do more than just preventing future assaults from
> external moisture and fingerprint chemicals?

There are not so many ways. The best way is, just to store them in a dry
environment, ideally with relative humidity <40%, better <20%. Use silica
gel as desiccant. Important is to change the desiccant from time to time.
Don't touch interior parts with bare hands as salt will get on the specimen
which will lead to first corrosion.

> 2.  Will long soaks in anhydrous alcohol help individuals, and polished
slices?

It does only help if the specimen got wet before. Then, it can help to
quickly pull out the water. Otherwise (with a dry specimen) it can even hurt
as alcohol is hygroscopic (it will attrack water from the air humidity). Use
alcohol only in combination with a postbake in an oven at about 80 deg. C.
DONT DO such things with fresh (observerved falls) carbonaceous chondrites
like CMs or CIs. The alcohol will remove pristine organic compounds and the
temperature can already alter such meteorites.

> 3.  Has anyone successfully used Steve Schoener's iron stabilization
formula for individuals and polished
> slices of ordinary chondritis (i.e., a mix of water, alcohol, and NaOH)?

NEVER use any chemicals, lacquers, solvents, inhibitors, rust removers etc.
on (valuable) stony meteorites!!!! All such agents will very likely alter
the meteorite. Such a treated meteorite is LOST to science!!! And: if such
treatments have been done and this is not known to the scientist who will
study/analyse such a meteorites in the future, it creates lots of confusion,
puzzling question on measurement results and additional investigations and
at the end lot of wasted time.

So, don't even consider doing such things to stony meteorites - just keep
them dry and prevent contamination, including fingerprints, dust, etc.!

Best regards,
Jörn Koblitz / MetBase


> 4.  Does anybody know of a good online sources where an
> average Joe can
> purchase anhydrous alcohol?


> -----Ursprüngliche Nachricht-----
> Von: Stephen McMann [mailto:stephen_mcmann at hotmail.com]
> Gesendet: Montag, 20. Dezember 2004 17:37
> An: meteorite-list at meteoritecentral.com
> Betreff: [meteorite-list] Sweaty Fingers, Chlorides, and Chondrites
>
>
> Dear List,
>
> Over the past few years there has been much discussion about
> preserving
> irons, but little discussion about rust prevention in
> ordinary chondrites.
> However, chondrites can of course suffer from the same
> problems as irons,
> presumably exacerbated by the same culprits (internal
> moisture, internal
> chlorides, fingerprints from previous owners, etc.).  Unfortunately,
> chondritis tend to be more complex chemically and so I'm not
> certain about
> how to deal with these problems in a way that gives display
> specimens long,
> stable lives.
>
> Here are some naïve questions:
>
> 1.  Can one easily do more than just preventing future assaults from
> external moisture and fingerprint chemicals?
>
> 2.  Will long soaks in anhydrous alcohol help individuals,
> and polished
> slices?
>
> 3.  Has anyone successfully used Steve Schoener's iron
> stabilization formula
> for individuals and polished slices of ordinary chondritis
> (i.e., a mix of
> water, alcohol, and NaOH)?
>
> 4.  Does anybody know of a good online sources where an
> average Joe can
> purchase anhydrous alcohol?
>
> Sincerely,
> Stephen McMann
> ______________________________________________
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
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