[meteorite-list] Tumbling Weathered-up Stony Chondrites

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Sat, 23 May 2009 23:02:21 -0400
Message-ID: <e51421550905232002s11839f95ke183f91d6298a0a7_at_mail.gmail.com>

Hi Tom,

I think I saw some of those same Ghubara tumbled fragments on eBay not
too long ago. It's part of what gave me the idea.

I wish I had taken before photos of the UNWA before I tumbled them.
But, it's pretty easy to imagine what they looked like - these were
extremely weathered-up and ugly with no remaining traces of crust.
These were completely sandblasted with no desert varnish or wind
polish - so they were near the bottom of the UNWA desirability ladder.

After tumbling for one week with coarse grit, the result can be seen
at the link below. In the photo, the meteorites are on the left side
of the tray and there is petrified wood on the right side.

Compared to other things I have tumbled, there was more loss with the
meteorites. When I opened the barrel, the usual slurry was much
thicker and "puffy" with an distinct rust coloration to it. Given the
weathered and fissured nature of these UNWA fragments, the water must
have caused considerable and rapid oxidation which broke down the
matrix of the stones. Individual pieces lost anywhere from 33% to 50%
of their mass.

The result is pleasing though - all of the stones are now rounded and
some appear "oriented" as a result of the process. Even before the
polishing stages, they are much improved in appearance compared to how
they looked to start with. One stone in particular looks very nice -
it is seen in the second photo. It has an orange matrix with
noticeable chondrules and prolific metal flecks. I am hoping it
survives the process to final polishing.

Note, the stones are still wet in the photos.

http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/tumbled-1.jpg

http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/tumbled-2.jpg

I'll check in again next week after the next stage of tumbling is complete. :)

Best regards,

MikeG

On 5/22/09, STARSANDSCOPES at aol.com <STARSANDSCOPES at aol.com> wrote:
> Hi Mike, I bought a few Kg. of small Ghubara fragments that were tumbled.
> The before and after results were cool! They looked awful before tumbling.
>
> I have never tried it myself but I have put dirty samples in walnut shells
> in a brass tumbler dry for cleaning.
>
> My call on the water would be to substitute rubbing alchohol for the water.
> It's cheap and it really draws out any water.
>
> Tom
>
>
> In a message dated 5/22/2009 3:28:26 PM Mountain Daylight Time,
> meteoritemike at gmail.com writes:
> Hi Listees!
>
> I have a Lortone Rock Tumbler (QT66 with two 6-lb barrels) and I
> decided to put some very ugly and extremely-weathered up UNWA stones
> into it - just to see what the result is. They have been tumbling in
> coarse grit for 6 days now - tomorrow night I will open the barrel,
> check them, and decide if they will need another coarse grit stage
> before moving on.
>
> Has anyone on the list ever tumbled meteorites? And what result did
> you get? I am worried about water intrusion deep down into the
> specimens, so I assume a good baking in the oven will be called for
> when the tumbling is done?......or would something like silica gel be
> better?
>
> Best regards,
>
> MikeG
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-- 
.........................................................
Michael Gilmer (Louisiana, USA)
Member of the Meteoritical Society.
Member of the Bayou Region Stargazers Network.
Websites - http://www.galactic-stone.com and http://www.glassthrower.com
..........................................................

Received on Sat 23 May 2009 11:02:21 PM PDT