Pseudomalachite

Formula: Cu5(PO4)2(OH)4

Colour: Blue-green, green, dark green, green-black; green to bluish green in transmitted light.

Lustre: Vitreous

Hardness: 4 – 4½

Specific Gravity: 3.6 – 4.34

Crystal System: Monoclinic

Name: From the Greek ψευδής for “false” for its similarity to, but not being, malachite.

Type Locality:  Virneberg Mine (St Josephsberg Mine), Rheinbreitbach, Unkel, Neuwied District, Rhineland-Palatinate, Germany

Polymorph of: Ludjibaite, Reichenbachite

Isostructural with: Cornwallite

A secondary mineral found in oxidized zones of copper deposits. The phosphate analogue of Cornwallite. The monoclinic polymorph of Ludjibaite; a monoclinic variant polymorph of Reichenbachite. More common than both polymorphs. Maybe be intergrown with Ludjibaite and Reichenbachite; in these cases, the pseudomalachite nearly always appears to be older and darker.