This Specimen has been sold.
4.6" Golden Calcite Crystal with Sphalerite and Barite - Elmwood Mine
Here is a beautiful, gemmy, golden-yellow calcite crystal from the famous Elmwood mine. The calcite is partially covered in white barite crystals, with black sphalerite crystals peppered across the specimen. There is a section of dolomite encrusted matrix that the calcite likely originally formed from.
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. Its fracture is conchoidal, but difficult to obtain.
Sphalerite is a part of the sulfides group and typically exhibits a grey/black appearance due to high concentrations of impurities. When sphalerite is in it's purest state, the chemical composition is ZnS, and can display a gemmy transparent light tan/yellow color. This is one of the few minerals that can form crystals ranging anywhere between gemmy and transparent to opaque and metallic-like. Opaque or cloudy sphalerite tends to be most abundant, due to the ease of iron replacing zinc in the process of formation.