[meteorite-list] Meteorites most resistant to oxidation?

From: Michael Gilmer <meteoritemike_at_meteoritecentral.com>
Date: Fri, 1 Apr 2011 22:36:27 -0400
Message-ID: <BANLkTikjPtOm4QJi+oYVLx+kcskSEmB2zQ_at_mail.gmail.com>

Hi Melanie and List,

One thing to keep in mind about meteorites and oxidation/stability is
the processing.

Any meteorite can be made unstable by contamination. For example,
cutting a meteorite with tap water is asking for trouble. The
chlorine in the tap water will contaminate the specimen and guarantee
a future of problems and a ruined specimen. If water is used as a saw
coolant, it should be distilled water only.

Another thing to keep in mind is that a sick/rusting meteorite is not
a lost cause - it can be decontaminated using a variety of methods
that have been discussed on this list previously. Some methods work
better/quicker/cheaper than others and opinions vary on what method is
best. One thing is for certain - merely cleaning the outer surface of
a sick meteorite will not cure the problem. Sanding, wiping with
petroleum products, baking in an oven, etc, will only produce
temporary results.

The best way to ensure a stable specimen is to keep it free of
contamination in the first place. When purchasing specimens with a
reputation for rusting, ask the dealer/seller how the meteorite was
processed. Was tap water during cutting or polishing? If chlorinated
water was used, then politely pass on that specimen.

I have 4 slices of Brenham sitting in my cabinet right now, all of
them are completely stable and rust-free, even down here in humid
Florida. Using dessicants, my cabinet's ambient humidity level hovers
between 30-40% (which is not as dry as I would like, but this is
Florida afterall), and they have shown no sign of rusting over several
months. They are absolutely stable and will hold up just as well as
any pallasite. This is because they were thoroughly decontaminated by
Pat Mulvany.

A few years ago, I bought a slice of etched Brenham from Robert Ward.
I owned it and displayed it in southern Louisiana and Florida for
almost 3 years and it never rusted. Whoever did the processing on
that slice knew what they were doing.

So, part of the rust equation is the meteorite itself, but an equally
important part is the processing and possible contamination.

Melanie - your sick Brenham that is losing olivines can be saved, but
nothing short of total decontamination will preserve it in the long
term.

Best regards,

MikeG

----------------------------------------------------------------------
Mike Gilmer - Galactic Stone & Ironworks Meteorites

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-----------------------------------------------------------------------

On 4/1/11, Melanie Matthews <miss_meteorite at yahoo.ca> wrote:
> Murray Lake seems to be a special case. From what i read, a protective crust
> formed on the outside of the meteorite as a result of weathering.. When cut
> has
> it been found to be more stable than any other iron meteorite? Also, i've
> read
> that Seymchan and the Springwater pallasits, are quite stable too. My
> Brenhams
> are already rusting and the olivines falling out..
>
>
> -----------
> -Melanie
> IMCA: 2975
> eBay: metmel2775
> Known on SkyRock Cafe as SpaceCollector09
>
> I eat, sleep and breath meteorites 24/7.
>
>
>
> ----- Original Message ----
> From: Shawn Alan <photophlow at yahoo.com>
> To: miss_meteorite at yahoo.ca
> Cc: meteorite-list at meteoritecentral.com
> Sent: Thu, March 31, 2011 11:23:20 PM
> Subject: [meteorite-list] Meteorites most resistant to oxidation?
>
> Melanie and Listers,
>
> That's a great meteorite you have there. Another meteorite you might want to
> check into is Murray Lake for resistant to oxidation. Its the oldest known
> and
> intact meteorite that has been recovered. The age of the meteorite is around
> 120
> million years old. That's sometime it has spent on Earth.
>
> Here is a link to read up on the find by Dr LaPaz
> http://articles.adsabs.harvard.edu/full/seri/Metic/0001//0000109.000.html
>
> Shawn Alan
> IMCA 1633
> eBaystore
> http://shop.ebay.com/photophlow/m.html
>
>
> [meteorite-list] Meteorites most resistant to oxidation?Melanie Matthews
> miss_meteorite at yahoo.ca
>
> Thu Mar 31 23:26:37 EDT 2011
>
>
> Previous message: [meteorite-list] AD - Benguerir Japan Benefit Auction
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>
> Hi list,
> Which meteorites would you say are known to be the least susceptible moister
> and
>
> oxidation? I have two slices of NWA 5234 melted eucrite (one of the
> prettiest of
>
> meteorites imo) and the material seems very stable - i've had them for over
> a
> year, handled them quite a bit and they show no signs of rusting.. *knocks
> on
> wood*
>
>
> So I wager it'd be some of the achondrites that have the least amounts of
> iron
> and other components reactive to oxygen... which meteorites are they
> (name/designation and class)?
>
>
> -----------
> -Melanie
> IMCA: 2975
> eBay: metmel2775
> Known on SkyRock Cafe as SpaceCollector09
>
> I eat, sleep and breath meteorites 24/7.
>
>
>
>
>
>
> Previous message: [meteorite-list] AD - Benguerir Japan Benefit Auction
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>
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--

Received on Fri 01 Apr 2011 10:36:27 PM PDT