Comparison of calculated heat conductivities of porous chondritic material and measured data given in Yomogida & Matsui (1983) with some additional data from Opeil et al. (2012). Lower solid black line: least-squares fit to data (filled cyan squares: H chondrites; filled circles: L chondrites). Red symbols: results of a numerical simulation including some pore space corresponding to porosity φ (crosses: H chondrite; open squares: L chondrite material). The blue filled squares are measured values for sandstone (Desai et al. 1974). Solid green lines: Simulated sintered granular material. Solid green line with circles: Sintered granular material of glass beads described in Sect. 4.2. The lilac lines are for crack-like voids simulated by the Bruggeman mixing rule with rotational ellipsoids of the indicated axis ratio as inclusions. Upper solid black line: Approximation (19) for sintered material.