Hello John, Elton and List,
John and Elton were discussing the use of a core drill to remove a sample
from meteorites for aesthetic reasons. I've have used this technique on one
meteorite I have. It is an Angrite, NWA 4931 which, at the time, I did not
want to cut in order to get to the center material for scientists at MIT to
perform magnetism analysis.
Here is my description of NWA 4931 with photo links of the coring and
overall meteorite:
NWA 4931, the Main Mass to the now famous angrite, NWA 2999. NWA 4931 has a
Total Known Weight (TKW) of 2140 grams in two interlocking fragments, which
form a complete stone. Surprisingly, the two parts were recovered by nomads
months apart in the Sahara Desert in 2007. The first 1314-gram half was
flown to Massachusetts Institute of Technology in Boston where scientists
extracted a core sample in order to conduct magnetism tests, which they
hoped would provide vital evidence indicating the size of the Angrite Parent
Body (APB).
Image of 1314-gram stone representing 60% of entire mass (cube: 1-inch
square):
http://www.lunarrock.com/nwa4931/nwa4931complete1.jpg
Link to image of core sampling at MIT laboratory:
http://www.lunarrock.com/nwa4931/nwa4931core.jpg
Image of 66-gram complete slice displaying abundant xenocrysts:
http://www.lunarrock.com/nwa4931/nwa4931slice.jpg
An international consortium of scientists, led by Dr. Benjamin Weiss of MIT,
took a new approach to the problem by testing samples from several angrites
with an extremely sensitive magnetometer. They discovered the material
showed evidence of ancient magnetic fields similar to those of rocks formed
on Earth within the planet's magnetic field. In other words, as the team
reported in the October 31, 2008 issue of Science, these 4.56
billion-year-old meteorites once were part of bodies that were either big
enough or hot enough to produce central, molten, metallic cores.
Link to LPSC abstract on magnetic field on Angrite Parent Body:
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2143.pdf
"The meteorites, therefore, are essentially magnetic recording tapes," says
Weiss. The magnetic fields that they recorded were probably generated by
molten metal swirling around inside the planet's core like a giant, rotating
dynamo, as happens on Earth. Angrites are among the oldest known pristine
basaltic meteorites ever found and have provided new clues about the
conditions that existed at the beginning of the solar system, solving a
longstanding mystery and overturning some accepted ideas about the way
planets form. They still contain magnetic records about the earliest stages
of planet formation and differentiation.
ScienceNOW Daily News: October 30, 2008:
http://sciencenow.sciencemag.org/cgi/content/full/2008/1030/2
Science October 31, 2008:
http://www.sciencemag.org/cgi/content/abstract/322/5902/713
Link to abstract reporting ages of angrites NWA 2999, NWA 4801 and NWA 4590
"Tamassint":
http://www.lpi.usra.edu/meetings/metchron2007/pdf/4061.pdf
BSE image of corona textures in NWA 4931.
http://www.lunarrock.com/nwa4931/nwa4931bse.jpg
<<
I have never announced or offered any of NWA 4931 publicly, but this may be
as good a time as any. If anyone is interested in a large slice of an
important Angrite, I can send a list of what is available. If there is
enough interest, I will post the availability list here.
Best regards,
Greg
====================
Greg Hupe
The Hupe Collection
NaturesVault (eBay)
gmh...@htn.net
www.LunarRock.com
IMCA 3163
====================
Click here for my current eBay auctions:
http://search.ebay.com/_W0QQsassZnaturesvault
----- Original Message -----
From: "Mr EMan" <mstrema...@yahoo.com>
To: <meteorite-list@meteoritecentral.com>; "John Hendry" <p...@pict.co.uk>
Sent: Saturday, September 12, 2009 10:34 AM
Subject: Re: [meteorite-list] Willamette cutting question
Hello John
Circular diamond coring bits only came into use recently. The Willamette
donation was in the early 1900's. I can only assume that the saw method of
the time dictated the location of the cut: large heavy frames using a wire
loop with abrasives hand fed into the grove. It is not like one could
easily rotate the mass easily.
I am happy to see the use of core sample extraction more frequently in
sampling. However, coring has a drawback in that it is very difficult to
lubricate and can heat up the core changing some magnetic states.
Elton
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