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.