Abstract

MAURELIA, R. et al. CARACTERIZACION Y SEPARACION DE UNA ESTILBITA ORIGINARIA DE LA REGION DE ATACAMA, CHILE. Bol. Soc. Chil. Quím. [online]. 2000, vol.45, n.4, pp. 569-575. ISSN 0366-1644.  http://dx.doi.org/10.4067/S0366-16442000000400007.

The properties of natural stilbite from the Atacama region of Chile are described in this work. This mineral shows colorless, white and honey-brownish shades, and it presents pearly and vitreous luster with a radial crystallization form. The results from the physical and chemical characterization are 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 composition 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-free orthorhombic zeolite (stilbite is recognized as monoclinic), suggesting the presence of two different crystal growing sectors. The IR spectrum shows the characteristic O-H stretching and bending and the symmetric and asymmetric T-O (T: Si, Al) stretching absorption bands. Gravitational combined with magnetic separation methods seems to be appropriated for separating the stilbite from the associated gangue.

Keywords : Natural zeolite; stilbite; characterization; isolation.