A glass or glass powder is fused from a starting mixture containing approximately 38 wt % to 48 wt % SO2, 15 wt % to 19 wt % Al2O3, 4.5 wt % to 11 wt % TiO2, 0 wt % to 1.5 wt % Na2O, 0 wt % to 1.5 wt % K2O and 23 wt % to 30 wt % CaO. In addition, a glass powder mixture includes two glass powders, a carbon black powder and an organic binder, the first glass powder having a mean particle size of approximately 150 &mgr;m to 250 &mgr;m, the second glass powder having a mean particle size of less than approximately 100 &mgr;m, which may be 10 &mgr;m to 70 &mgr;m. The glass or glass powder mixture is suitable for producing a glass ceramic, such as that used as a resistor seal and/or a gas-tight glass ceramic solder in a spark plug.