The structure and properties of the glass can be modified by introducing appropriate additives. Dolomite is one of the primary raw materials modifying the properties of glass, in which the essential component is calcium-magnesium double carbonate CaCO₃∙MgCO₃. The paper presents the research results on glasses obtained by smelting pure amphibolite and amphibolite modified with 10 and 20% dolomite additives. The raw material used was mined in the Poland region of Lower Silesia. The glass melting process was carried out in an electric furnace at 1450 °C for 2 h. The structure and properties of the glasses and crystallization products were determined by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy—Energy Dispersive Spectroscopy (SEM-EDS). Viscosity and Vickers microhardness were also measured. It was found that the modification of amphibolite glass by adding dolomite affects the glasses’ properties and structure. The research results determined the effect of dolomite addition on the properties of alumino-silicate glasses in terms of the mineral fibre products used in the construction industry.

The paper presents the results of studies on the viscosity of the glass mass in various temperature ranges, determining the basic technological parameter, very important from the point of view of melting and forming. For this purpose, six sets based on natural raw materials such as basalt, dolomite, and amphibolite, modified with different amounts of float glass cullet, were melted. The melting process was carried out in an electric furnace at the temperature of 1450 °C for 2 h. Using the dilatometric method, high-temperature microscopy and theoretical calculation methods, the viscosity of the produced glasses was determined in various temperature ranges. Comparative analyses of the employed methods were carried out. The significance of the applied calculation methods for aluminosilicate glasses depending on the basic chemical composition of the glasses was presented. The relationship between the manner of incorporating amphoteric ions Al³⁺, Fe³⁺ and Mg²⁺ into the glass structure and the change in viscosity in the temperature range corresponding to the working point range at 10⁴ [dPa·s] viscosity and the relaxation range—T_g temperature at 10¹³ [dPa·s] viscosity was justified. It was justified that in order to plot the viscosity curve with the correct slope in the forming range for aluminosilicate glasses, it is appropriate to use the two-point method based on the fixed viscosity points of 10⁴ [dPa·s] and 10¹³ [dPa·s].

The paper presents research on multicomponent glasses obtained from natural and secondary raw materials, i.e., basalt, amphibolite, and cullet. The raw materials were used as potential sets to produce mineral fibres or glass-ceramic materials. FTIR spectroscopy and XRD studies were carried out to identify the composition of the phase type in the glass sets. The results were supported by SEM-EDS microstructural studies of the obtained materials. The ability of the melts to crystallize and their basic properties required in producing mineral fibres, i.e., the hardness and the acidity modulus, were also determined. In the glass samples after the crystallization process, the spectroscopic studies revealed an increase in the half-width of the band at 1200–800 cm⁻¹ and splitting at the values of about 870 cm⁻¹ and 970 cm⁻¹. These changes probably indicate the formation of pyroxene-type crystalline phases. Moreover, based on the XRD results, it was confirmed that the obtained materials were fully amorphous. After annealing at 800 °C for 2 h, the materials show a small proportion of crystalline phases. For the materials annealed at higher temperatures, clear peaks from the crystalline phases were represented mainly by pyroxenes. The proportion of crystalline phases in the samples was also found to rise with increasing temperature, and the hardness values for the basalt glasses and glasses after crystallization rose from 753 to 946 HV0.05. Such an effect positively affects the properties of the obtained glass-ceramic materials based on the proposed sets. However, in the case of mineral fibres, crystallization at early 2 h at 800 °C can be a disadvantageous feature from the point of view of their application because crystalline phases can lead to fibre damage after a short period of operation; this will be confirmed in this study.