5.6" Gemmy, Twinned Calcite Crystal Cluster - Elmwood Mine
This is a phenomenal 5.6" long cluster of large, twinned calcite crystals from the famous Elmwood Mine in Carthage, Tennessee. These large crystals are a light honey color and very lustrous.
The Elmwood Mine is a zinc mine in Carthage, Tennessee which opened in 1969, before being closed for many years, only to be reopened in 2010. It has produced many world class specimens of Fluorite, Calcite, Barite and Galena over the years. Specimens used to be plentiful as miners were allowed to recover specimens, but collecting is strictly prohibited by the new mine owners. They've gone to great lengths to prevent the mining of specimens, including blasting crystal pockets or filling them with slurry.
Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form.