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May-June 2017

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Who's Who in Mineral Names: Rodney C. Ewing (b. 1946)

Ewingite, Mg8Ca8(UO2)24(CO3)30O4(OH)12·138(H2O), is a rare secondary uranium mineral. It was named in honor of Rodney C. Ewing, professor of geological sciences, Frank Stanton Professor in Nuclear Security, and Senior Fellow at the Freeman Spogli Institute for International Studies at Stanford University, Stanford, California. He is also the Edward H. Kraus Distinguished University Professor Emeritus in the Department of Earth and Environmental Sciences at the University of Michigan and Regents' Professor Emeritus at the University of New Mexico. The naming of ewingite recognizes Ewing's exceptional contributions to the understanding of the behavior of actinide elements (U, Th, and others) and their minerals in near-surface settings, particularly as they relate to nuclear waste disposal (Olds et al. 2016). Ewingite was discovered underground in the Vladimír shaft, Plavno mine, Jachymov district, Bohemia, Czech Republic, on oxidized uraninite. It is bright yellow and is associated with uraninite, gypsum, pyrite, chalcopyrite, sphalerite, galena, liebigite, and a variety of other secondary uranium species. Ewingite crystals have tetragonal symmetry, are as large as 2 mm, and tend to be crude in form, suggesting some amount of dissolution. Ewingite has a very complex structure; in fact, based on the formula defined by Krivovichev (2012), it is the most structurally complex mineral yet discovered (Olds, pers. comm., 2016). 

 

Dr. Christopher J. Stefano is the associate curator at the A. E. Seaman Mineral Museum

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