Earth Earth is metamorphic rock, which is created from the transformation of pre-existing rock types through high pressures, high temperatures, or both. The most abundant silicate minerals on Earth's surface include quartz, feldspars, amphibole, mica, pyroxene and olivine. Common carbonate minerals include calcite (found in limestone) and dolomite. The elevation of the land surface varies from the low point of at the Dead Sea, to a maximum altitude of at the top of Mount Everest. The mean height of land above sea level is about . The pedosphere is the outermost layer of Earth's continental surface and is composed of soil
Silicate minerals that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living things also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons ("tests") from silica extracted from seawater. The tests of dead diatoms are a major constituent of deep ocean sediment, and of diatomaceous earth. A silicate mineral is generally an ionic solid whose anions consist predominantly of silicon and oxygen atoms. In most minerals in the Earth's crust, each silicon atom is the center of an ideal tetrahedron,