3.25" Iridescent Scalenohedral Calcite Crystal Cluster - Moldova

This is an alluring cluster of scalenohedral calcite crystals with a thin coating of iridescent chalcopyrite. The specimen was collected from a location near the Dniester River in Moldova.

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.
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DETAILS
SPECIES
Calcite & Chalcopyrite
LOCATION
Dniester River, Moldova
SIZE
3.25 x 1.7"
CATEGORY
ITEM
#301458