2.1" Sparkling Dioptase Crystals with Mimetite - N'tola Mine, Congo

This is a beautiful cluster of sparkling, gemmy dioptase crystals that formed in association with yellow-orange mimetite, collected from the N'tola Mine of the Republic of the Congo. This mine has been closed since 2019, so this material is old stock. The entire specimen is 2.1" wide and the dioptase is a lustrous, emerald-green color.

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.

Mimetite is a lead chloro-arsenate mineral with the chemical formula of Pb5(AsO4)3Cl. Depending on conditions, during formation/replacement, arsenate radicals (As04) can be replaced by a phosphate (PO4) or vanadate (VO4) radical. This alteration is what leads to the formation of pyromorphite and vanadinite, hence why they're typically found associated with each other. Regularly ranging between red and yellow in color, mimetite can occur in a variety of structures, from small prismatic clusters and crusts, to incredible hexagonal crystals both thick and thin.

Dioptase & Mimetite
N'tola Mine, Mindouli, Mindouli District, Pool Department, Republic of the Congo
2.1 x 1.5"