3.3" Iridescent Chalcopyrite and Calcite on Dolomite - Missouri

This is a gorgeous, 3.3" wide association of hexagonal-columnar calcite crystals, iridescent chalcopyrite crystals, all on a dolomite crystal encrusted matrix. This mineral cluster was collected from the Sweetwater Mine in Reynolds County, Missouri, a site known for its stunning mineral associations.

It comes with an acrylic display stand.

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.

Chalcopyrite is a brass-yellow colored mineral and an important copper ore. When weathered, chalcopyrite loses its metallic luster, turning a gray-green color. When exposed to acids, the tarnish can develop a red, blue, or purple iridescence: this acid-treated material is often sold under the name peacock ore.
Calcite, Chalcopyrite & Dolomite
Sweetwater Mine, Viburnum Trend, Reynolds County, Missouri
Entire specimen: 3.3 x 2.7"