Physical properties of ordinary chondrites

Physical properties (intrinsic and bulk densities, porosity, compressional and shear wave velocities, thermal diffusivity, and conductivity) are measured on 11 ordinary chondrites, one carbonaceous chondrite, and two achondritic clasts of a mesosiderite. With the previously reported results from Antarctic ordinary chondrites, the data are useful in clarifying the difference between H and L chondrites. For example, the intrinsic density of H chondrites (∼3800 kg/m3) is generally higher than that of L chondrites (∼3600 kg/m3). The sample porosity, less than 20%, strongly controls its elastic wave velocities, thermal diffusivity, and conductivity. The variations of elastic wave velocities and thermal properties with porosity show that as with lunar rocks, chondrites contain many cracks. These cracks are thought to be created on their parent bodies by the cumulative effects of many mutual collisions and impacts. Thermal properties are linear functions of elastic wave velocities for both H and L chondrites. The difference between H and L chondrites can be attributed to the content of metallic Fe‐Ni. Correlations between petrologic types, which roughly represent metamorphic temperature, and porosity are less obvious for L chondrites than for H chondrites. Since porosity is not changed significantly by impact events, it appears that the sintering process for L chondrites is independent of the metamorphic events represented by petrologic type.