Thanks Darren and Elton
It just shows how naive I am about metal detection ! I never used one...
But I am surprised that my post didn't get more response, as well as the
ones from Darren
that I mentioned in my first post:
1- "Possible Ohio crater" in Apr. 2005: not one response to it !
Another Mecca or alike ?
2- "The wonderful wizards of Osmium" (Apr 2008): few answers, but nothing
about the unique extraterrestrial signature of Osmium compared to Iridium
(end of that post)
The search on the archives yielded only 279 hits for Iridium, most of them
about Ir flares
or the Iridium satellite network.
Is this list maybe not the "right" place for such discussion ?
and if not, is there another list discussing such aspects ?
Thanks
A bientot
Michael B, France
----- Original Message -----
From: "Mr EMan" <[email protected]>
To: <[email protected]>; <[email protected]>
Sent: Monday, March 16, 2009 6:11 AM
Subject: Re: [meteorite-list] Iridium (+ Osmium ? + Technetium ?)
measuringand testing
Hello Darren The original post never made it to my mail box. To the
original posters questions about metal detectors:
One of the points to be made is that a metal detector only detects free
metal not elements. It is a "field test" and searching for specific
elements is a "lab test'
As they say on the American TV Game Show-- Family Feud --"gudanzer"! my I
say--"gudlinks".
Elton
--- On Sun, 3/15/09, Darren Garrison <[email protected]> wrote:
>A- measuring on the field/ meteorite finding/ first testing:
>I read often that finders/hunters use magnets. What
about a metal detector measuring Iridium ?
>or is Iridium detection too close to other elements, or too small in
>content to be singled out ? and what about Osmium ? or Technetium ?
>
>B- testing
>How is Iridium (or Osmium, or Technetium) analysed and
tested ? Is there any non-invasive way to test one or more of
them, to keep the meteorite "as is" ?
I was sitting here trying my best to remember the name of a
type of measurement used to find very small amounts of atoms in materials
(as is often the case) it
wasn't coming to me. Fortunately I remembered it being
described in a book by Walter Alverez called T. rex and the Crater of
Doom,searched down my copy and was reminded that it is "neutron
activation analysis". Good book on the
detective work behind the discovery of the iridium (and
other rare element) concentrations at the K/T boundary. You should try
to get your hands on a copy. You can preview big chunks of it on Google
Books:
http://books.google.com/books?id=kkHhl67ixwEC&printsec=frontcover&dq=rex+and+the+crater+of+doom#PPA66,M1
Use the right-hand search window to search for
"neutron activation analysis" in
the book.
http://en.wikipedia.org/wiki/Neutron_activation_analysis
As for technetium, I wouldn't hold my breath about
finding much of it. Very
short half life, both in human terms for some isotopes
(hours to days) and in cosmic terms (at most a few million years, a blink
of the eye in the age of a
meteorite). The amount (from some googling) produced
naturally by uranium decay and neutron absorbtion in molybdenum seems to
be vanishingly small. Doesn't
look to be much to be a mesurable amount to picked up from
the solar wind (though this article is pretty old)
http://www.new.dli.ernet.in/rawdataupload/upload/insa/INSA_1/20005aca_407.pdf
Here's an article touching on the decay products of
technetium in meteorites:
http://wwwsoc.nii.ac.jp/jnrs/paper/JN63/jn6325.pdf
and another:
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1877.pdf
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