Rocks are made up of one or two minerals. They are categorised into threes categories that are igneous, sedimentary, and metamorphic rocks. When rocks disintegrate they form soil.
1 Additional Answer
Rocks are often made up of the solidification of rock, debris and the chemical or physical modification of heat and pressure. Rocks are also composed of minerals that form into crystal like structures. You can find more information here: http://www.physicalgeography.net/fundamentals/10d.html