A ceramics having improved thermal shock resistance is produced by a method comprising firing a mixture comprising at least one compound selected from the group consisting of sulfate, nitrate, carbonate, oxide, hydroxide, acetate and oxalate of an alkali metal and an alkaline earth metal, titanium oxide, rehydratable alumina, optionally silica and optionally a rare earth element compound at a temperature in the range of 1,000°C to 1,300°C.