The Florida State University Tallahassee, Florida 32306 Department of Geology

Dr. Robert V. Gentry Earth Science Associates 10/27/89 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. Sincerely, A. Leroy Odom