Crystallizing phases from multi-component silicate glasses in the system K2O-CaO-MgO-Al2O3-SiO2

The sequence of crystallization of phases in some glasses based on anorthit e-diopside-forsterite containing 10-40% (wt.%) K-feldspar was studied. Phas e association, transformation and extent of solid solutions development hav e been followed by X-ray diffraction, polarizing microscope, indentation mi cro-hardness was also measured. Diopside and anorthite were the primary cry stalline phases and small amounts of microcline in K-feldspar-poor glasses. With increasing soaking time and temperature of heat-treatment, forsterite was developed meanwhile microcline was transformed into orthoclase. With a n increase of K-feldspar to 40%, the anorthite phase disappeared and forste rite was transformed into enstatite while sluggish transformations of micro cline into orthoclase were observed, The sequence of crystallizing phases i s found to be as follows: diopside, anorthite, forsterite, microcline, then the orthoclase. (C) 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved.