<h3><u><em>Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors.</em></u></h3>
Ammonification refers to chemical reactions in which amino groups (NH2) associated with organic forms of nitrogen are converted into ammonia (NH3) or ammonium (NH4+).