Abstract
The albite synthesized from the gels of NaAISi3O8 composition in the system Na2O-Al203SiO2-H2O-CO2 has been investigated. The obliquity 2θ(131)-2θ(1_??_1) indicated that all the synthetic albites are of intermediate type according to the definition of albite polymorph given by Martin (1969). X-ray powder patterns for synthetic intermediate albite are reported for the first time. Some of synthetic albites are produced as single crystals, with which the intensity of reflection was measured by means of four-cricle diffractometer. The RF value; F1ko-F1_??_o/F1ko+F1_??_o proposed here seems convenient to characterize the structural state of albite polymorph. The IR spectra of these intermediate albites and its glass are reported in detail. In the DTA curve of high albite, an intersection. point 1116±7°C of the endothermic peak shows a striking similarity to the melting point, 1118±3°C, of albite suggested by Schairer and Bowen (1956). Polymozphism of the intermediate albite is discussed on the basis of the fact that some of natural and synthetic intermediate albites deviate from the linear trend between obliquity and their cell parameters.
