Chemical Composition: The black firebricks consist of various oxides with the following percentages: Na2O (0.5%), MgO (1.2%), Al2O3 (11.4%), SiO2 (45.3%), SO3 (1.8%), K2O (3.0%), CaO (17.9%), TiO2 (0.7%), MnO (8.7%), Fe2O3 (8.2%), NiO (0.6%), CuO (0.5%), and C (0.4%).

Physical & Mechanical Properties: The apparent density is 2.07 g/cm³, while the real density is 2.86 g/cm³. The open porosity is 27.41% p.v., and water absorption is 13.45% p.w. The cold crushing strength is 38.44 MPa, and the flexural strength (M.O.R) is 9.53 MPa.

Thermal Properties: The refractoriness is greater than 1100°C, with a permanent linear change of less than 1%. Thermal conductivity is 1.15 W/m·K at 200°C and 1.04 W/m·K at 400°C. The heat capacity is 0.76 J/g·K. Thermal diffusivity is 7.7·10^-7 m/s at 200°C and 7.0·10^-7 m/s at 300°C.