[meteorite-list] Question About Potassium-Argon (K/Ar) dates for North American and Australasian Tektites

From: Norm Lehrman <nlehrman_at_meteoritecentral.com>
Date: Tue, 14 Oct 2008 12:02:25 -0700 (PDT)
Message-ID: <785596.34697.qm_at_web81002.mail.mud.yahoo.com>

Michael & list,
  
Greetings from Tanzania! Sorry to be so out of touch, but electricity and internet service are both pretty insecure here.

Michael, K-Ar and Ar40/Ar39 techniques are not limited to volcanic rocks. Anything containing potassium (certainly including tektites) can work. There are always interpretative issues, but that's another subject.

I spend a fair bit of my field time here working with geochronology where 2.8 billion years is "young" and an error bracket of +/- 40 million years is almost too sloppy to be of use! I'm learning some new stuff.

No meteorites so far, and virtually no decent search environments. I found a killer little iron in the middle of a jungle trail a while back, but a quick zap with a Niton portable XRF unit showed no Ni. Just a nice chip off of an iron plow or sledge hammer---.

The Niton ray gun is driving me crazy. At virtually no cost, I can pull the trigger and analyze for the entire periodic table heaver than Na in less than 1 minute. This machine should be able to let us non-destructively differentiate iron meteorites, and maybe tektites. Why am I going crazy? ALL my collection is in storage in the USA and I can't test the technology! The unit costs around $35,000 US. Here, now, I have unlimited access to one, and soon, several.

Imagine being able to instantly (in relative terms), go though a collection of irons and verify their identity. I've got some in my collection that are potentially with the wrong tag, and I bet every museum in the world fits into that fellowship. What if we can easily zap tektites to confirm/differentiate Ivorites, Bediasites, and Australasians? Authenticate moldavites and reject etched glass? I THINK this tool is in our hands now.

I'm coming to the US at Christmas time. Who can offer me a nice wide variety of approx. 1 cm sq slices of irons at a decent price? I could even return them afterwards (subject to the risk of confiscation in customs somewhere---). If this works as I think it could, I'd consider buying a Niton on my return to the USA, and offering verification services.

If anyone is able to provide me with a dozen or so little iron chips (for a price of course), please let me know. This could be very cool.

Regards to all,

Norm
http://tektitesource.com



, 10/14/08, Michael L Blood <mlblood at cox.net> wrote:

> From: Michael L Blood <mlblood at cox.net>
> Subject: Re: [meteorite-list] Question About Potassium-Argon (K/Ar) dates for North American and Australasian Tektites
> To: bristolia at yahoo.com, "Meteorite List" <meteorite-list at meteoritecentral.com>
> Date: Tuesday, October 14, 2008, 10:56 AM
> Hi Paul & all,
> K-A dating is only applicable to volcanic material,
> therefore,
> It would not be applicable to tektites.
> Best wishes, Michael
>
> on 10/14/08 9:14 AM, Paul at bristolia at yahoo.com wrote:
>
> > Dear Friends,
> >
> > Can anyone recommend a publication that provides a
> > comprehensive listing of Potassium-Argon (K/Ar) dates
> > that have been published for the North American and
> > Australasian tektites?
> >
> > Also, what the authorative reference(s) work for
> > the bulk composition of tektites from each of these
> > strewn fields?
> >
> > Any citations, which you can recommend would be
> > greatly appreciated.
> >
> > Best Regards,
> >
> > Paul H.
> >
> >
> >
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Received on Tue 14 Oct 2008 03:02:25 PM PDT