Then these sedimentary rocks are buried, subjected to heat, pressure, and fluids, and become metamorphic rocks. Eventually, these metamorphic rocks may be heated to the point where they again melt into magma. It is also possible for rocks to remain un-eroded and unchanged in stable regions for long periods of time. These paths are represented by the arrows running through the centers of the circles in the figure above and in Figure 3.10. Having briefly dealt with the other classes of rock and the rock cycle, let's move on to discuss igneous rocks in more detail.
Igneous rocks are rocks which form from cooling magma or lava.
Magma Molten or partially molten rock material and dissolved gases. Magma is molten rock beneath Earth's surface. Lava Molten or partially molten rock material and dissolved gases. Lava is molten rock which has erupted at Earth's surface. Whether or not the rock has holes, or vesicles , in it.