Cast Stone Matrix Based on Comelts of Basalt and Metal Oxides: Part I. System Basalt–M_xO_y (M = Sr, Ln)

This work examines cast stone matrices (CSM) fabricated by comelting basalt and Sr, Ln (Ce, Nd, Gd) oxides. Matrices containing glass and clinopyroxene as the major phases were established to be resulted from the comelting of basalt with SrO. Strontium partially replaces calcium in clinopyroxene, but mostly enriches the melt in contact with crystallizing clinopyroxene. When this melt cools, glass is formed containing up to 31 wt % SrO. The doping of basalt with oxides of rare earth elements (REE) M_xO_y: CeO₂, Nd₂O₃, Gd₂O₃ taken in a weight ratio of 4 : 1 and 2 : 1, results in the formation of CSM, the main permanent phases of which are glass and clinopyroxene. In addition, magnesioferrite can crystallize from a basaltic melt upon cooling, and phases of cerianite CeO₂ or britholite Ca(Nd,Gd)₄(SiO₄)₃O can crystallize depending on the basalt/M_xO_y weight ratio.