Clinoclase - Encyclopedia
Class : Phosphates, arsenates, vanadates
Subclass : Anhydrous arsenates
Crystal system : Monoclinic
Chemistry : Cu3(AsO4)(OH)3
Rarity : Uncommon
Clinoclase (sometimes also called clinoclasite) is a secondary arsenate from the oxidation zone of arsenic-rich copper deposits. Its name comes from the Greek klino (to lean) and klasis (to break), due to its oblique basal cleavage in relation to the main faces. In its deposits, clinoclase is usually part of a large procession of secondary copper minerals (chrysocolla, malachite, cornubite, etc...) mixed with goethite. The crystals are essentially flattened needles up to 5 mm, gathered in rosettes or fibroradiated spherolites measuring up to 5 cm ; pseudorhombohedral prismatic crystals are rarer, as are encrustations. The color is dark greenish blue to greenish black.
Main photo : Clinoclase from Majuba Hill Mine, Nevada, USA © Vincent Bourgoin
Clinoclase in the World
Twinning
No twins known for this mineral species.
Fakes and treatments
No fake identified for this mineral species.
Hardness : 2.5 to 3
Density : 4.38
Fracture : Irregular
Streak : Blue-green
TP : Translucent to transparent
RI : 1.730 to 1.910
Birefringence : 0.180
Optical character : Biaxial -
Pleochroism : Low
Fluorescence : None
Solubility : Acids
Magnetism : None
Radioactivity : None