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 anorthite-diopside-forsterite containing 10-40% (wt.%) K-feldspar was studied. Phase association, transformation and extent of solid solutions development have been followed by X-ray diffraction, polarizing microscope, indentation micro-hardness was also measured. Diopside and anorthite were the primary crystalline 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 an increase of K-feldspar to 40%, the anorthite phase disappeared and forsterite was transformed into enstatite while sluggish transformations of microcline into orthoclase were observed, The sequence of crystallizing phases is 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.