The rock cycle is the process where minerals are converted into different forms by processes such as melting, cooling, eroding, o compacting. In this cycle, the matter that makes up the rocks is never destroyed or created it simply changes into different forms, therefore, this is an example of the law of conservation of matter. A similar cycle is the cycle of water, where the water of the earth is warm by the sun and evaporates then when it elevates to the atmosphere it cools and is condensed again into a liquid and falls back to the earth to begin the cycle. In this case, the water is not created or destroyed in simply changes into different states.