Datolite is an interesting and widely distributed mineral that, although often occurring in handsome specimens, is commonly overshadowed by the wonderfully crystallized zeolites with which it is often associated. It is well known from the trap rocks of the northeastern United States and is noted as a gangue mineral in some ore deposits. Besides the tourmalines, it is one of the few silicates that contains relatively abundant boron, and, as such, it has been mined as an unlikely source of that element in unusual Russian deposits. Because it is commonly available in fine, modestly priced specimens at most mineral shows, and its attractive nodules have been described recently in the various serialized articles on the Michigan Copper Country by Tom Rosemeyer (including the one in this issue), datolite has been suggested as the topic of this Connoisseur's Choice feature.
Dr. Robert B. Cook, an executive editor of Rocks & Minerals, is a professor emeritus in the Department of Geology and Geography at Auburn University, Auburn, Alabama. He welcomes suggestions for this column and can be contacted at the addresses above.

