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
Latent heat systems that were intentionally held at constant temperature. Such usage referred to "latent heat of expansion" and several other related latent heats. These latent heats are defined independently of the conceptual framework of thermodynamics. When a body is heated at constant temperature by thermal radiation in a microwave field for example, it may expand by an amount described by its "latent heat with respect to volume" or "latent heat of expansion", or increase its pressure by an amount described by its "latent heat with respect to pressure". Latent heat is energy released or absorbed, by a body or a thermodynamic