* The Rock Cycle: Rocks are constantly changing through a process called the rock cycle. Metamorphic rocks form when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are subjected to intense heat and pressure deep within the Earth's crust.
* Melting is Key: To become igneous rock, a rock must melt into magma (molten rock). Metamorphic rocks, while subjected to heat and pressure, don't necessarily reach the melting point.
* The Transformation: For a metamorphic rock to become igneous, it needs to:
* Melt: This usually occurs when the rock is subducted (pushed down) into the mantle where temperatures are high enough to melt it.
* Cool and Crystallize: The magma then rises to the surface or cools within the Earth. As it cools, it solidifies and crystallizes, forming igneous rocks.
In summary: The transformation from metamorphic rock to igneous rock involves melting, followed by cooling and crystallization. It's not a direct transformation but a step in the ongoing rock cycle.
