The complex dielectric properties of rocks are interesting scientifically and important practically. The scientific interest derives from a desire to understand the properties of materials, the electrical structure of the earth's crust, and the (electrical) loss mechanisms in the crust. The practical significance stems from potential applications in borehole logging, geothermal prospecting, mineral prospecting, and in lithospheric radiowave communications. The real part of the permittivity (epsilon') of a rock is an average of the permittivity of the individual minerals; the volume fraction of each mineral appears to be a suitable weighting function for most purposes. The loss factor (epsilon'') obviously depends on the various loss mechanisms present and on the frequency. In rocks, the value and behavior with temperature and frequency are dominated by the water (and dissolved ions) present in microcracks. In this study, we have removed the water from the microcracks in order to obtain data suitable for use in inferring the properties of rocks at depths where the microcracks are not present. Such depths may be as shallow as 1 km.