CHABAZITE
Class : Silicates
Subclass : Tectosilicates
Crystal system : Triclinic
Chemistry : CaAl2Si4O12
Rarity : Common
Chabazite belongs to the group of zeolites, hydrated aluminosilicates made up of a framework crisscrossed with channels into which water and large cations are inserted. Its name comes from the Greek chabazios (melody), it designates one of the twenty stones of the poem Peri Lithos which exalted the virtues of minerals and attributed to Orpheus. Chabazite lines the cavities of basic volcanic rocks (basalts and andesites), in association with other zeolites. it is also known in fissures in metamorphic shales and limestones, and as precipitate from thermal springs. It forms rhombohedral crystals (unique case among zeolites), pseudocubic with striated faces, which commonly compose twin buildings by interpenetration, or by adjoining along the faces of the rhombohedron ("phacolite" facies, rich in faces). Chabazite is colorless, white, sometimes yellowish or a surprising salmon pink. Chabazite channels have a diameter of 3.8 Å, making this mineral (and several other zeolites) an excellent molecular sieve for hydrocarbons. It is also used in the nuclear industry for the extraction and fixation of radionuclides possibly present in residual effluent solutions from reactors; chabazite fixes radioactive cesium and strontium in particular.
Main photo : Chabazite from Gamlarett Quarry, Kirkjubøur, Streymoy, Faroe Islands © Volker Betz
Chabazite in the World
Twinning and special crystallizations
Twins are known and common around [0001], interpenetrating, simple and repeated or contact on {10-11}.
Fakes and treatments
No fake identified for this mineral species.
Hardness : 4 to 5
Density : 2.05 to 2.2
Fracture : Conchoidal
Streak : White
TP : Translucent to transparent
RI : 1.478 to 1.493
Birefringence : 0.002 to 0.006
Optical character : Biaxial (+/-)
Pleochroism : None
Fluorescence : Variable
Solubility : Hydrochloric acid
Magnetism : None
Radioactivity : None