Celadonite - Encyclopedia
Class : Silicates
Subclass : Phyllosilicates
Crystal system : Monoclinic
Chemistry : K(Mg,Fe)2Si4O10(OH)2
Rarity : Quite common
Celadonite is a micas group mineral that crystallizes in altered volcanic rocks of basic to intermediate composition, where it replaces ferromagnesian silicates. It reflects light metamorphism (zeolite facies), or the action of late hydrothermal solutions and then fills the cavities of the andesites and basalts. It is notably associated with montmorillonite, prehnite and zeolites. Its name comes from the French “céladon” which designates a pale green color like that of the mineral. It forms tiny micaceous-looking lamellae, and earthy aggregates usually pale olive green to bluish green in color.
Main photo : Celadonite from Terra do Baptista, Madeira, Portugal © Pedro Alves
Celadonite in the World
Twinning and special crystallizations
No known twin.
Fakes and treatments
No fake identified for this mineral species.
Hardness : 2
Density : 2.95 to 3.05
Fracture : Micaceous
Streak : White
TP : Translucent to transparent
RI : 1.606 to 1.662
Birefringence : 0.027
Optical character : Biaxial -
Pleochroism : Visible
Fluorescence : None
Solubility : Hydrochloric acid
Magnetism : None
Radioactivity : None