Dr. Robert V. Gentry
Earth Science Associates
Dear Dr. Gentry,
It was nice to hear from you. I am enclosing samples of the Addaba and Granitville
granites. Enclosed also is a copy of a note published in the January issue of
Geology which gives a bit more detail regarding the measurements of the halos.
As I said over the telephone, such halos are quite rare in these samples.
I might also mention that the three giant halos are the only halos we have seen (i.e. we
have not found halos of what would seem to be normal size). I should also emphasize
that we were not searching for halos. Jack Rink found the first by chance.
Since we have only two complete halos, we feel obliged to keep them for
documentation in case anyone wishes to observe them. All color centers are readily
destroyed by heat and produced by ionizing radiation. We hope that you are
successful in finding additional specimens from the material we are sending. We
will be carefully looking for these in our future selections of quartz grains
for ESR analyses, and would be glad to send you ones we find.
The Science paper was the result of an accidental finding; it is not something
that we are really working on. As is obvious in the paper, we have proven nothing
— simply offered an alternative explanation. We had included a question mark
at the end of our title of the paper, but it was removed apparently by the editor.
Jack and I would be very happy to see you investigate these halos, and if possible test our model.
I told you that I would send you the editorial comments about our reference to
an "instaneous creation" as a suggested explanation for the Po halos. I now recall
that these comments were made on the edited manuscript which I had to return with
our revision. The editor suggested that we leave this reference out of our
paper, but we felt that a reader new to the subject should be aware of other
explanations that had been offered.
Our original manuscript had to be cut 30%. We had included a summary of the very
detailed work you have done on the subject over the years. We had also
included discussion on why we did not think previously offered explanations for
giant halos in mica could account for those we have found in quartz. We could
not do this for Po halos, for we actually do not have a Po halo.
If our interpretation of the smoky halos is correct, I would expect that giant
halos in quartz would be the most common type. Accordingly, I would also expect
that these haloes would be relatively common in those rocks in which monazite
inclusions in quartz is relatively common. This is why I suggested you might
consider the samples Owens studied by cathodoluminescence (reference is given
in our Geology note). Owens did not see the smoky halos, because he was
working with thin sections of rocks. I do not believe that even our Addaba
specimen would be visible in thin section. You might try contacting Owen for a
sample of the rock.
You said you were preparing a paper on Po halos. I would be very interested
in having a copy, when you have completed it. I hope that we can be of some help
to you. Thanks for the phone call, and let us know what you find. Jack and I are
quite curious about these things. If you are ever in the vicinity, please stop by.
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Sincerely,
A. Leroy Odom |
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