In many areas of geophysics, geology, geochemistry, and mining, there is considerable interest in laboratory data on the physical properties of various types of rocks. Until recently, how ever, only the mechanical properties of rocks had been studied in detail. The last few years have seen a relatively large amount of study of the electrical properties of rock samples and a need to organize the results of these studies has arisen. In"Electrical Properties of Rocks,"* E. 1. Parkhomenko reviewed and cataloged studies of electrical resistivity and the dielectric constant in rocks. In the present work she covers other electrical phenomena which are observed to occur in rocks and minerals and reviews the re sults of her own researches, as well as that of others, previously published. Theoretical and experimental data on the piezoelectric prop erties of minerals and rocks obtained since 1953 by E. 1. Parkho menko and myself as the result of laboratory investigations on quartz-bearing rocks (granite, gneiss, quartz veins, etc. ) comprise the bulk of the monograph (Chapters1-4). Itwas not previously con sidered that a polycrystalline mass such as a rock could exhibit piezoelectric properties - it was supposed characteristic only of single crystals."

Recently there has been growing interest in the physical properties of rocks. To interpret data on the geophysical fields observed near the Earth's surface, we must know the physical properties of the materials composing the interior. Moreover, the development of geophysical methods (in particular, electrical methods) is necessitating a multiple approach to the study of the physical properties of rocks and minerals. In connection with problems now appearing, the physical properties of rocks must be studied in the laboratory under var ious thermodynamic conditions. Electrical methods of geophysi cal exploration often may require only data obtained at atmos pheric pressure and room temperature, or at temperatures below 100 DegreesC. If, however, we have in mind geophysical field observa tions on the composition and state of matter deep in the Earth's crust and mantle, we must conduct laboratory experiments at high pressures and temperatures. For example, in interpreting data from geomagnetic soundings of the mantle, we may need experi mental results on the electrical properties of rocks at pressures of tens of kilobars and temperatures of the order of lOOO DegreesC. In this connection, we must remember that pressure has relatively little effect on the electrical properties of rocks, whereas, tem perature affects them very strongly. v vi FOREWORD At present, while research into the mechanical properties of rocks (relating to the problems of geophysics, geochemistry, geology, and mining) is pressing forward on a wide front, much less work is being done with electrical properties.