Monopyroxenic basalt-based glass-ceramics

Uniform, ultrafine, microcrystalline, hard, pyroxenic glass-ceramic materia ls have been obtained successfully from basalt rock; instead of adding nucl eation catalysts, the FeO:Fe2O3, CaO:Na2O, and CaO:MgO ratios have been rec tified. This process has been accomplished by deliberately adding the small est permissible amounts of oxidizers, limestone, dolomite, and soda ash (as additives) that are necessary to fulfill the monominerality requirements; these requirements affect the melting, workability, crystallization, and mi crostructure of the glass-ceramics, The melting temperature decreases as th e ratios decrease (beyond certain limits); in addition, the workability, cr ystallization, and microstructure also improve as the ratios decrease. An a lmost-stable solid solution of augite or aegirine-augite composition is the only crystalline phase that is formed. The minimal FeO:Pe(2)O(3) ratio and the likelihood of a greater affinity of the Na+ cation for the Fe3+ cation , rather than the Al3+ cation, may be responsible for increasing the stabil ity and widening of the crystallization field of the complex aluminum-beari ng pyroxene solid solution.