Metamorphic rock the foliation is called "gneissosity"), granoblastic (includes granulite, some marbles and quartzite), and hornfelsic (includes hornfels and skarn). Metamorphic rock Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure ( or more), causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by
Heat of dilution The heat of dilution can be defined from two perspectives: the differential heat and the integral heat. The differential heat of dilution is viewed on a micro scale, which is associated with the process in which a small amount of concentrated solution is added to the mass dilute solution. The molar differential heat of dilution is thus defined as the enthalpy change caused by adding a mole of a concentrated solution at a constant temperature and pressure. Because of the small amount of addition, the concentration of dilute solution remains unchanged. Mathematically, the molar differential heat of dilution is denoted