Why is there oxygen in the Earths Crust?

Answer 1

Oxygen, though usually a gas, is still in a molecule form and can be bonded to with any other molecule that is able to do so. Oxygen is a very common element in the crust because many rocks and more importantly minerals that make up those rocks use it in there atomic bonds. A simple example is Quartz, SiO2 So each single structure has one silicon atom and two oxygen atoms.

Answer 2

Oxygen in the Earth's crust is primarily bound in minerals such as silicates and oxides. These minerals are formed through various geological processes over millions of years, leading to the presence of oxygen in the crust. Additionally, oxygen can be incorporated into rocks and minerals through the weathering and oxidation of the Earth's surface materials.