Many things can form a rock. Solidification of magma, compaction of sediment, and recrystalisation (metamorphosis) resulting from heat and pressure are main ones.
Rock cycle here: http://www.teachnet-lab.org/ps101/bglasgold/rocksEFCycleP2.gif
igneous rock
A foliated metamorphic rock forms when crystals combine and form visible bands
Metamorphic rock forms by the pressure on large masses of rock, causing the existing minerals in the rock to recrystallize without melting, resulting in new minerals and textures. Examples of metamorphic rocks include marble, slate, and schist.
igneous rock
An extrusive igneous rock.
A metamorphic rock forms by heat and pressure
Igneous rock. Extrusive igneous rock forms at or near the surface, intrusive igneous rock forms below the surface.
Igneous rock. Extrusive igneous rock forms at or near the surface, intrusive igneous rock forms below the surface.
That would be sedimentary rock, and (honorable mention) occasionally metamorphic rock.
A "metamorphic" rock forms.
The rock that forms on earth's surface is extrusive rock or otherwise known as a metamorphic rock.
The melting of metamorphic or igneous rock forms magma.
Sedimentary rock forms due to the accumulation and compression of sediments, while metamorphic rock forms due to the alteration of existing rock through heat and pressure. Igneous rock forms from the cooling and solidification of magma or lava.
metamorphic rock
Igneous Rock comes from molten rock.
Contact metamorphic rock forms at such boundaries, as the minerals in the rock change due to the increase in temperature or the influx of heated fluids.
Igneous rock