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March-April 2009

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Letters

CLASSIC GEOLOGY
Three cheers for the Russian geologists! In the “Diamonds of Russia” article (November/December 2008), the story of the first kimberlite pipe discovered by Larisa Popugaeva is a story of classic geology. With no computers, no GIS, no satellite imagery, just down-and-dirty field geology, she paved the way for the discovery of one of the largest diamond deposits on the planet. For me, a field collector of minerals and fossils for thirty years, this is what it’s all about—treasure hunting. This geologic vignette should be read to every freshman geology student on the first day of class.

Jeff Smith
Pittsburgh, Pennsylvania

Figure 1

Figure 2

Figure 3

HEMISPHEROIDAL FLUORITE
Subsequent to finishing my article on “Hemispheroidal Fluorites from India,” in the July/August 2008 issue, I was shown an interesting specimen of one of these fluorites that behaved in an extraordinary way. The piece when handed to me was white in color (fig. 1), but when wet with either acetone or water (fig. 2), it turned red (fig. 3). With acetone this change was almost instantaneous; with water it took perhaps a full minute to turn red. Upon drying, the fluorite returned to its original beige color. Again, with acetone the drying was very quick, but with water it took several minutes for the red color to disappear.

The owner of the piece, Jürgen Tron, and I agreed upon a logical explanation. We think that beneath the beige surface of the dry fluorite the hemisphere is coated with a red film. There is a thin white layer of an opaline material over the red film that obscures the red. The opaline layer is porous such that when it is wet it becomes transparent, thus allowing the red film to be seen. Upon drying, the top layer turns beige and once again masks the red beneath it. We did not attempt to wet the top layer with oil, but we suspect that it would have the same effect and would also greatly extend the drying period, meaning that the hemisphere would remain red for a very long time.

I would like to point that this is a rare phenomenon. Most of the red fluorites from the trap rocks in India are not coated by such a film, and their red color is not enhanced by treatment with oil or any other liquid.

John S. White
Stewartstown, Pennsylvania


GREENSTONE CORRECTION
In my Word to The Wise column titled “Greenstone,” in the November/December 2008 issue, I wrote: “When iron is in its divalent oxidation state (Fe2+), as is found in such minerals as olivine, pyroxenes, amphiboles, chlorites, and epidote. . . ." I want to thank Edward Grew, from the University of Maine, for pointing out to me that this is not completely correct, and that the last mineral in this list, epidote, Ca2(Fe3+,Al)3(SiO4)3(OH), is one of the few common silicates to contain Fe3+ only, and its color is due to ferric iron. A detailed description of Fe3+ crystal field transitions in epidote and the cause of color can be found in Mineralogical Applications of Crystal Field Theory by Roger Burns (Cambridge University Press, 1993).

John Rakovan
Department of Geology
Miami University
Oxford, Ohio

AFMS SCHOLARSHIP FOUNDATION
The American Federation of Mineralogical Societies (AFMS) Scholarship Foundation grants for 2008 have been issued to students in the regional federations. To date, a total of $1,300,000 in scholarships has been awarded to deserving graduate students since the first grant was made in 1965 for $300. The generous support of the AFMS societies and their members has made this possible.

The following is a list of the students currently receiving grants and the honorees who were chosen to select them.

California Federation: Prof. George Wheeldon, of Shingle Springs, California, selected Ben Schumer, University of Nevada (Reno), and Matthew Lesh, California State University (Sacramento).

Eastern Federation: Prof. Emeritus Arthur M. Hussey, of Bowdoinham, Maine, is the honoree; recipients have not yet been named.

Midwest Federation: Nellie and Joe Claxton, of Mt. Vernon, Illinois, selected Steve Boles and Samuel G. Roy, Southern Illinois University (Carbondale).

Northwest Federation: R. Ed Romack, of Ketchum, Idaho, selected Kelly M. Whitehead and Joseph W. Sheffield, Idaho State University (Pocatello).

Rocky Mountain Federation: Anna M. Domitrovic, of Tucson, Arizona, selected Madison C. Barkley and Renata R. Jasinevicius, University of Arizona (Tucson).

South Central Federation: Dr. Bridget M. Joubert (Marier), of Alexandria, Louisiana, selected Daniel Lupton and Jacob F. Grosskopf, University of Texas (San Antonio).

Dee Holland, President
AFMS Scholarship Foundation
Tendoy, Idaho

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