To provide a method for producing a piece of low-temperature baked rigid and high-strength earthenware used for building or an ornament, sufficiently firmly sinterable while retaining the shape of a molded product by low- temperature baking at ≤1,000°C and having an extremely wide range of baking temperature.

Fine particles of kaolinite or halloysite having ≤3.0 μm average particle diameter and fine particles of calcium carbonate having ≤2.0 μm average particle diameter as fine particle components are compounded in a ratio of (45:55) to (75:25) expressed in terms of weight ratio and a somewhat coarse granular quartzite powder having 3-50 μm average grain diameter is compounded with the fine particle components in a ratio of (90:10) to (60:40) based on the fine particle components to provide a ternary mixture as a fundamental component. Thereby, a raw material mixture containing ≥80% ternary mixture is prepared and molded into a desired shape. The molded product is then baked at ≤1,000°C temperature to afford a piece of crystalline low-temperature baked rigid and high-strength earthenware consisting essentially of anorthite and quartz and having ≥60 MPa bending strength.