Ceruleite - Encyclopedia
Class : Phosphates, arsenates, vanadates
Subclass : Hydrated arsenates
Crystal system : Triclinic
Chemistry : Cu2Al7(AsO4)4(OH)13 12H2O
Rarity : Very rare
Ceruleite is a copper and aluminum arsenate from oxidized zones of arsenic-rich polymetallic deposits. It is commonly of recent formation in mine galleries. It takes its name from the Latin caeruleus (azure) because of its color. Ceruleite forms microscopic crystals, assembled into powdery encrustations, chalky concretions or spherical aggregates of up to 10 cm, pale blue to sky blue, sometimes dark blue.
Main photo : Ceruleite from Wheal Gorland, St Day, Cornwall, England, UK © Gianfranco Ciccolini
Ceruleite in the World
Twinning
No twin known for this mineral species.
Fakes and treatments
No fake identified for this mineral species.
Hardness : 5 to 6
Density : 2.70 to 2.80
Fracture : Irregular
Streak : White to pale blue
TP : Translucent
RI : 1.60
Birefringence : -
Optical character : Biaxial
Pleochroism : None
Fluorescence : None
Solubility : Hydrochloric acid and potash
Magnetism : None
Radioactivity : None