Gorgeous, 2.3" Dioptase, Shattuckite & Calcite Association - Congo

This is a 2.3" wide association of calcite, royal to light-blue shattuckite and dioptase that was collected from the Tantara Mine in the Democratic Republic of Congo. This specimen is unique in that it features a double pseudomorph. The blue, scalenohedral crystals are shattuckite after dioptase after calcite. These pseudomorphs can be seen in the cropped in photos above.

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.

Shattuckite is an scarce copper mineral that is highly regarded for its vivid blue color. It is named after the Shattuck Mine in Bisbee, Arizona, where this mineral was first discovered. It crystallizes in the orthorhombic – dipyramidal crystal system and usually occurs in a granular massive form and also as fibrous acicular crystals.

Dioptase is an uncommon mineral found mostly in desert regions where it forms as a secondary mineral in the oxidized zone of copper sulfide mineral deposits. This copper based mineral forms small rhombohedral crystals, typically less than 0.75 cm in length.
It is popular with mineral collectors due to its vibrant color and it is occasionally cut into small emerald-like gems.
Dioptase, Shattuckite & Calcite
Tantara Mine, Shinkolobwe, Katanga Province, DR Congo
2.3 x 1.8"