You start off with any type of rock all rock can melt into magma. It goes through the melting stage, and melts until it turns into magma itself
The magma finds a way out of the volcano onto the ground. It cools and crystallizes into a Igneous rock. The black rock is the Igneous rock.
The Igneous rock gets weathered and eroded by the rain and turned into sediment. The Igneous rock goes through a process of breaking down the rock to turn into sediment.
The sediment gets compacted and cemented together to make a sedimentary rock. It gets compacted and cemented together by strong forces of wind, but mostly water. (I looked it up)
The sedimentary rock goes through the process of heat and pressure. Because it gets hot and then the pressure applies to it changes the rock into a metamorphic rock. The heat allows it to be changed and the pressure changes it into a metamorphic rock.
The metamorphic rock melts into magma. It gets turned into magma because the magma melts it. You start off with what you started with magma, but the metamorphic rock is the one that is melting this time not just any type of rock .