Relative dielectric constant from dry rocks

Relative dielectric constant is an important physical factor in the theory of microwave remote sensing and electromagnetic transmission. This note reports the results of detecting relative dielectric constant from 197 rock samples. The regular pattern of the relative dielectric constant varying with microwave spectrum is revealed. The relative dielectric constants, correlated with the type, density, structure and chemical component of the rock, are discussed. The results are: ( i ) The relative dielectric constant is related to the frequency when it is measured within the frequency of 0.5–18 GHz. ( ii ) The real part of the relative dielectric constant among different types of rocks changes in a large range, the regular pattern of the change is from ultrabasic rock, basic rock, to intermediate rock, acid rock and sedimentary rock. The real part of relative dielectric constant gradually lowers, the change range is between 9 and 5. ( iii ) The real parts of relative dielectric constant have a marked positive correlation with the density of the rocks. ( iv ) The relative dielectric constant related with the structures of the rocks, the smaller the grain of rock, the larger the relative dielectric constant. ( v ) The real parts of relative dielectric constant related to chemical component of the rock are more complex. The imaginary parts of relative dielectric constant are markedly correlated with MnO and LOI, less correlation with Fe₂O₃, FeO, MgO, P₂O₅, and has no correlation with the rest variables.