[meteorite-list] Contamination during cutting - what impact does it have on analysis?

From: Michael Blood <mlblood_at_meteoritecentral.com>
Date: Tue, 18 May 2010 18:37:42 -0700
Message-ID: <C8188EF6.E850%mlblood_at_cox.net>

Hi Michael,
        I use the cutting rust preventative by Bill Mason that you
Mix with distilled water (just a little goes a long way, making
It very inexpensive). Bill is the developer/inventor of all the
Paleobond products, but then got into meteorites. He knows
His stuff.
        After slicing I put the slices in 96% alcohol (I can get it in
Mexico). Regular "rubbing alcohol" is like 30% water - you want
As little water as possible, as the alcohol soaks up the water, then
Rapidly evaporates.
        I then set them on a paper towel on a plate which
I put in the over to be super dried by the pilot light. Be sure
They are very dry before removing. Otherwise, you will likely
Be protected form rust due to the rest preventer, but your specimens
Will weigh out heavy and then get "lighter" as they dry out.
This time can be just a couple hrs for thin slices and 4 or 5 hrs
For very thick slices - more for end slices thicker than 5 or 6mm.
        To get this cutting agent see BILL MASON near the
Bottom of my home page:

http://michaelbloodmeteorites.com

For contact information.
        Best wishes, Michael


On 5/18/10 11:44 AM, "Met. Michael Gilmer" <meteoritemike at gmail.com> wrote:

> Hi List,
>
> I was wondering, while waiting for some freshly-sliced meteorites to
> cool in the oven, what kind of contaminants does cutting add to the
> meteorite? I am very careful and I only use distilled water as a
> coolant - to prevent chlorine contamination of the specimens. But I
> am sure that distilled water alters the specimens in some ways. Also,
> I use a diamond-coated blade during cutting, so might this impart some
> tiny diamond particles into the meteorite matrix?
>
> Let's assume an unclassified meteorite is sliced for classification -
> if the analysis detects diamond, is it easy to discern if the diamond
> was present prior to cutting or is it a contaminant from the cutting
> blade?
>
> On a molecular level, I assume that stainless steel is shed from the
> blade as well. Could this throw off elemental metal results? Besides
> cutting, consumer polishing also imparts particles from the sandpaper,
> buffing compound, rouge, or whatever else is used.
>
> I would imagine that NASA would use a sterile cutting tool and
> environment, but most meteorite collectors and dealers don't. So what
> exactly is in the prepared meteorite specimen you receive?
>
> Best regards,
>
> MikeG
Received on Tue 18 May 2010 09:37:42 PM PDT