Igneous rocks form when lava hardens on or below the surface of the Earth. Obsidian is an example of igneous rock.
Sedimentary rocks are formed by the accumulation or deposits of small particles and subsequent cementation of mineral or organic particles.
Metamorphic rocks are formed by existing rock types transforming into new rock through metamorphosis. Marble, quartzite and slate are examples of this type of rock formed by excessive heat and pressure.
Thank you for joining me down this rocky path...Tune in next week for my "Ted Talk!"