Characterization and isolation of a natural stilbite from Atacama region, Chile.

The properties of natural stilbite from the Atacama region of Chile are des cribed in this work. This mineral shows colorless, white and honey-brownish shades, and it presents pearly and vitreous luster with a radial crystalli zation form. The results from the physical and chemical characterization ar e the following: Mohs hardness = 3-4, specific gravity = 2.05, mass loss by heating = 17.4% and mass loss by HCl dissolution = 35.5%. The chemical com position is Na (0.59%), Ca (5.64%),Al (9.40%), Si+O (66.93%), H2O (17.44%). The X-ray diffraction patterns match also very well with stellerite, a Na-f ree orthorhombic zeolite (stilbite is recognized as monoclinic), suggesting the presence of two different crystal growing sectors. The IR spectrum sho ws the characteristic O-H stretching and bending and the symmetric and asym metric T-O (T: Si, Al) stretching absorption bands. Gravitational combined with magnetic separation methods seems to be appropriated for separating th e stilbite from the associated gangue.