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To guarantee the efficiency of solar thermal energy production, the thermal storage material must have exceptional resistance to thermal shock to withstand prolonged thermal cycles. In addition, it must have specific properties tailored to the requirements of this field. In this study, we developed a refractory cordierite for solar thermal storage, characterized by very high thermophysical properties, from an initial formulation containing 20 % of abundant clays. The properties of materials sintered at 900 °C, 1000 °C, 1100 °C, 1200 °C and 1250 °C were assessed by a series of analyses including X-ray diffraction (XRD), mass loss, volumetric shrinkage, bulk density, and porosity, scanning electron microscopy (SEM), thermal conductivity, thermal diffusivity, thermal storage capacity, chemical resistance, and mechanical testing. The incorporation of natural clays, rich in sintering aid elements, facilitated the formation of 74 % α-cordierite at 1200 °C and 92 % at 1250 °C, significantly enhancing the material's densification. Materials sintered at 1250 °C and containing 92 % refractory cordierite were subjected to 50 thermal shock cycles from 500 °C to 0 °C. The obtained materials showed excellent mechanical properties, including compressive strength of 398 MPa, low porosity of 0.21 %, density of 2.52 g/cm3, zero mass loss in acidic and basic environments for 30 days, and very high values of heat capacity (3429.80 J/(kg·K)), thermal conductivity (2.08 W/(m·K)) and thermal diffusivity (0.84 mm2/s) at room temperature.