2.55" Polished Calcite & Pyrite Sphere - Congo

This is a hand-polished sphere of calcite and pyrite from the Congo. There are small amounts of cobaltoan calcite that tint the sphere pink in some locations. Unfortunately the variety of mineralizations within the rock made it difficult to polish into a perfect sphere, leaving the specimen with a somewhat wonky appearance.

There are one spot of this sphere that has undergone epoxy filling, likely to assist with stability during the process of polishing.

Cobaltoan calcite, also known as cobaltocalcite is one of many different varieties of calcite, forming with a chemical composition of (Ca,Co)CO3. It crystallizes in a trigonal crystal system, and it forms rhombohedral or scalenohedral crystals. These crystals tend to display a pink color of which intensity can range anywhere from a pinkish-salmon to a hot pink.

Malachite is an intense green copper-based mineral that can be found in a wide variety of forms. Malachite can grow in botryoidal masses, stalactitic formations, and reniform formations, typically as a tight cluster of fanning fibrous needles that make up a seemingly solid mass. As layers continue to stack during formation, banded patterns can sometimes begin to take shape, explaining the rings in all shades of green seen on most polished malachite specimens.

Malachite results from the weathering of other copper ores, and is very often found associated with other copper-based minerals such as azurite and chrysocolla. It can be found in copper deposits around the world, but the Democratic Republic of the Congo is the primary source for polished malachite and mineral specimens.

Malachite has been prized since ancient times, first as a utilitarian copper ore, then as an ornamental stone. Due to its value as a decorative stone, it is rarely mined as a copper ore anymore.
Calcite, Calcite var. Cobaltoan & Pyrite
Katanga Province, Congo
2.55" wide