It was by applying high pressure as well as high pressure to carbon that man-made diamonds were first produced as well as many other interesting discoveries. Almost any material when subjected to high pressure will compact itself into a denser form, for example, quartz, also called silica or silicon dioxide will first adopt a denser form known as coesite, then upon application of more temperature, form stishovite. These two forms of silica were first discovered by high pressure experimenters, but then found in nature at the site of a meteor impact.
High pressure experimentation has lead to the discovery of the types of minerals which are believed to exist in core of the Earth, such as perovskite which is thought to make up half of the Earth's bulk, although no one has ever seen it on the surface.
Further Reading