Aurichalcite

Formula: (Zn,Cu)5(CO3)2(OH)6 Zn:Cu ratio is about 5:2, but may approach 2:1.

Colour: Pale green, sky blue, or greenish blue; colourless to light shades of blue or green in transmitted light

Lustre: Silky, Pearly

Hardness: 1 – 2

Specific Gravity: 3.96

Crystal System: Monoclinic

Name: A sage noted that the Aurichalcum (Latinized version of the Greek ορείχαλκος – “mountain copper”) of the ancients was “cuivre de Corinthe”, yellow copper or brass; in 1839, Th. Böttger named the mineral accordingly, in allusion to its copper and zinc content, the constituents of brass.

Type Locality:  Loktevskoye Mine (Loktevskii Mine), Upper Loktevka River, Altai Krai, Russia

A secondary mineral in copper and zinc deposits, aurichalcite is typically found as blue or green crusts or mats of tiny acicular crystals, often as feathery, tufted, druzes; more rarely it is found as columnar crystal aggregates or crusts of either lamellar aggregates or as granular aggregates.