Oxidation is a chemical reaction that occurs when a substance is exposed to oxygen. When rocks are exposed to oxygen in the air, the process of oxidation begins to break down the minerals in the rock. The oxygen combines with the elements in the rock to form new minerals, such as iron oxides and hydroxides. These new minerals are often weaker and less stable than the original minerals in the rock, which makes the rock more susceptible to weathering and erosion.

Oxidation can also cause rocks to change color. For example, when iron-bearing rocks are exposed to oxygen, the iron oxidizes and turns the rock a reddish color. This is the same process that causes rust to form on iron metal.

Oxidation is an important process in the weathering and erosion of rocks. It helps to break down large rocks into smaller pieces, which makes them easier to transport by wind and water. Oxidation also releases minerals into the soil, which can be used by plants and other organisms.