In this monograph, the boundaries of the definitions of a petrologist, geochemist, geophysicist or a mineralogist have been willfully eliminated to bring them all under the spectrum of high-pressure geochemistry when they deal with any material (quintessentially a chemical assemblage) - terrestrial or extraterrestrial - under the conditions of high-pressure and temperature. Thus, a petrologist using a spectrometer or any instrument for high-pressure studies of a rock or a mineral, or a geochemist using them for chemical synthesis and characterization, is better categorized as a high-pressure geochemist rather than any other kind of disciplinarian.
The contents of this monograph bring together, under one cover, apparently disparate disciplines like solid-earth geophysics and geochemistry as well as material science and condensed-matter physics to present a thorough overview of high pressure geochemistry. Indeed, such interdisciplinary activities led to the discovery of new phenomena such as high P-T behaviour in metal oxides (e.g. Mott transition), novel transitions such as amorphization, changes in order-disorder in crystals and the anomalous properties of oxide melts.