[meteorite-list] Why is aluminum foil better for protection?

From: karmaka <karmaka-meteorites_at_meteoritecentral.com>
Date: Sun, 29 Apr 2012 18:24:40 +0200
Message-ID: <1SOWvQ-0HdsYK0_at_fwd11.aul.t-online.de>

Hello Jim,
 
Maybe this is an answer:

"C2 carbonaceous chondrite falls with
 phyllosilicates in their matrices adsorbed volatile
 organic-carbon compounds from laboratory sample-
 storage materials within one day, between sample
 preparation and analysis"

from:
TERRESTRIAL WEATHERING OF CHONDRITES IN NATURE AND CONTINUING DURING
 LABORATORY STORAGE AND PROCESSING: REVIEW AND IMPLICATIONS FOR SAMPLE
 INTEGRITY. Michael A. Velbel

 http://www.lpi.usra.edu/meetings/lifedetection2012/pdf/6019.pdf

Best regards,

Martin
 
Von: "Jim Wooddell" <nf114ec at npgcable.com>
 An: "Meteorite-List" <meteorite-list at meteoritecentral.com>
 Betreff: [meteorite-list] Why is aluminum foil better for protection?
 Datum: Sun, 29 Apr 2012 17:50:32 +0200
 
Hi all!
 
 Being one that has always doubled plastic bagged finds, I would like to ask
 why aluminum foil is considered to be better at protecting from
 contamination?
 
 In fact, I witnessed two times where different techniques, aluminum foil and
 membrane boxes were replaced with plastic bags because there were issues
 with those techniques and stress to the specimens. And in those cases we
 did not have to be PhD's to see the stress placed on the specimens.
 
 I think this is a very important topic in handling meteorites.
 
 1. At the Sutter Mill fall, I watched NASA employee's handing out small
 squares of aluminum foil.
 This foil had been cut in squares about 5 or 6 inches square. It was
 removed out of a PLASTIC bag and then handed to those that needed it without
 the use of gloves and then some were folded up and placed in a pocket.
 So, technically, no one could tell you what was on that foil when a specimen
 was placed in it.
 2. The specimen had already been on the ground in an area that is moist
 from morning dew, etc. Additionally, it rained!
 3. Because people really wanted to see the specimens, the foil was
 constantly opened and close around the specimen. In one sample I looked at,
 crumbs were seen in the foil! Note that these appeared very delicate and
 once these samples were seen by us we all immediately made efforts at
 protecting them at best we could and gave good instruction on handling.
 
 To me, it was clear foil was a bad idea. And I know I can be totally wrong
 about such things. Most of us there immediately protected the specimens
 once seen. In fact, we were filmed using good technique in handing a very
 nice sample, using plastic bags and doubling them.
 
 1. Most people do not handle the inside of a plastic bag. So any
 contamination from the bag likely remains constant and can probably be
 predicted if it is that critical.
 2. The bags protected the sample by allowing people to view the sample
 without removing it from the bag as opposed to the aluminum foil constantly
 being opened and closed.
 3. The plastic surface was much more friendly to the surface of the
 specimens.
 
 4. Moisture in the bags could be better controlled if necessary by use of
 absorbent.
 
 So, how is aluminum foil better??? What do we protect the sample from better
 by using aluminum foil? Cosmic rays? I am missing something here and I
 would appreciate a good qualified answer because right now, from what I
 witnessed, it's a myth that does more harm than good!
 
 Anyways, I scored enough fragments and I am happy I did not skunk and I am
 glad Mike did not get bit by that rattle snake! I talked to a few of the
 locals and rangers in the area and they all said they do have a lot of
 rattle snakes in the area and now is when they come out. So those that are
 still there, be safe!
 
 Back home in AZ....now, what to do with those fragments! What awesome
 CAI's!!!
 
 Jim
 
 
 
 
 
 
 Jim Wooddell
 http://k7wfr.us
 
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Received on Sun 29 Apr 2012 12:24:40 PM PDT