2.1" Blue-Green Botryoidal Rosasite on Aurichalcite - Congo

Blue-Green Botryoidal Rosasite on Aurichalcite - Congo #312466

This is a gorgeous, 2.1" wide formation of botryoidal blue-green rosasite on sky-blue aurichalcite, collected from the Yanga Koubenza Quarries in the Republic of the Congo (Brazzaville). There appear to be tiny calcite crystals peppered across the rosasite.

The specimen has been mounted to an acrylic display base with mineral tack.

Rosasite is a secondary mineral that forms in oxidation zones of copper-zinc deposits, generally forming a fibrous botryoidal sphere that can appear vitreous and silky. While typically featuring a blue-green color, colorless specimens are not unheard of. The chemical formula of rosasite is CuZnCO3(OH)2.

Aurichalcite (chemical formula (Zn,Cu)5(CO3)2(OH)6) is a secondary mineral that forms in the oxidation zones of copper and zinc ore deposits. It often forms as radiating, fuzzy-looking acicular blue-green crystals and linings along cavity walls.

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