Atacamite Formula: Cu2(OH)3Cl System: Orthorhombic Colour: Bright green, dark ... Lustre: Adamantine, Vitreous Hardness: 3 - 3½ Libethenite Formula: Cu2(PO4)(OH) System: Orthorhombic Colour: Light to dark green, ... Lustre: Sub-Vitreous, Resinous, Waxy, Greasy Hardness: 4 Photo by: © Tóth László