18th century Italian fragments with calcite crystal in sphalerite from Elmwood Mine in Tennessee. It is an example of the world’s finest crystallized calcite. With the unusual formation of sphalerite, it is unequaled by those from any other part of the world (featured in American Mineral Treasures, pg. 337). These minerals are formed from the chemical precipitation of calcium carbonate and zinc. The minerals are essentially deposited on the walls, floors, and ceiling of the geological caverns of the zinc mine. It is known for producing some of the most superb various examples of calcite, fluorite, and sphalerite with exceptionally large and sharp calcite clusters.