Calcite is ubiquitous in the American Midwest where it occurs in a wide range of geological environments and frequently forms crystals of high quality, some with great complexity of form. It is the major constituent of limestone, most cave formations, and many fossil shells. North America's finest calcites are predominantly found in the American Midwest where large crystals occur in aesthetic combinations with such other well-crystallized minerals as barite, fluorite, galena, and sphalerite. Calcite crystals are classic components of Mississippi Valley–type (MVT) deposits, frequent occupants of open spaces within sedimentary rocks, and treasured finds in the very different, and much older, rocks that host the well-known copper mines and iron deposits of the upper Midwest. No other region on the continent can boast the same diversity of calcite. Yet, connoisseurship of fine minerals is not just about appreciation of specimen size and abundance; it is also about appreciating the variety of habits, color, luster and clarity, twinning, and interesting associations that may occur. With this in mind, we have nominated calcite from the interconnected Elmwood/Cumberland/Gordonsville mines in the Central Tennessee Lead-Zinc district as our Connoisseur's Choice; this locality is certainly among the very best calcite-producing localities in the world (see fig. 1).
Terry E. Huizing, a consulting editor of Rocks & Minerals, is adjunct curator of mineralogy at the Cincinnati Museum Center and focuses his personal mineral collecting activities on calcite, pseudomorphs, and minerals from the American Midwest.
R. Peter Richards, a consulting editor of Rocks & Minerals, is an Affiliate Scholar at Oberlin College and focuses his mineral collecting activities on interesting crystal habits, twinned crystals, and epitactic relationships.
Janet H. Clifford is a geologist by training though not by profession. An avid mineral collector for more than forty years, she enjoys field trips, exhibiting at mineral shows, volunteering at the Cleveland Museum of Natural History, and occasionally editing or writing for the hobby.
Dr. Robert B. Cook, an executive editor of Rocks & Minerals, is a professor emeritus in the Department of Geosciences at Auburn University.