The main component of the Earth's crust is oxygen, which makes up about 46% of its weight. The crust, which is the outermost layer of the Earth, is primarily composed of silicate minerals, many of which are compounds of silicon and oxygen. After oxygen, the next most abundant elements in the crust are silicon, aluminum, iron, calcium, sodium, potassium, and magnesium. These elements combine in various ways to form rocks, such as granite and basalt, which are fundamental to Earth's geology and structure.