Formula: Cu_2-xAl_x(H_2-xSi₂O₅)(OH)₄ · nH₂O, x < 1

Species: Silicates – (Phyllosilicates)

Colour: Green, bluish green, blue, blackish blue to black, or brown and rarely yellow

Lustre: Vitreous, Waxy, Earthy

Hardness: 2½ – 3½

Specific Gravity: 1.93 – 2.4

Crystal System: Orthorhombic

Name: The name was first used by Theophrastus in 315 B.C. and comes from the Greek “chrysos”, meaning “gold,” and “kolla”, meaning “glue,” in allusion to the name of the material used to solder gold. André-Jean-François-Marie Brochant de Villiers revived the name in 1808.

A mineral of secondary origin, commonly associated with other secondary copper minerals, it is typically found as glassy botryoidal or rounded masses or bubbly crusts, and as jackstraw mats of tiny acicular crystals or tufts of fibrous crystals. There are no known crystals of Chrysocolla. The chrysocolla “crystals” are all pseudomorphs. Copper-bearing allophane can look similar.