When metamorphic rock melts, it undergoes a transformation into magma. This process occurs typically when the temperatures and pressures in the Earth increase significantly, usually deep within the crust or in the upper mantle. The minerals within the metamorphic rock, which were previously altered by heat and pressure, now break down as the temperature rises to the melting point.
This melted material, known as magma, is a molten mineral mix that contains a variety of chemical elements and compounds. As it cools and solidifies, it can form igneous rock. Essentially, the metamorphic rock loses its structure and characteristics as it transitions back into a molten state, highlighting the dynamic nature of rock formation and the rock cycle.