Oxygen is the most abundant element in the Earth’s crust, making up about 46% of its weight. It is found combined with other elements, mainly in the form of oxides and silicates, which make up rocks and minerals. Oxygen is not found in pure form in the crust but is part of many compounds like quartz, feldspar, and clay minerals. Silicon is the second most abundant element and combines with oxygen to form silica and silicate minerals, which are the main building blocks of the crust. Aluminum and iron are also important but are less abundant. Oxygen’s presence is essential for many chemical reactions that shape the Earth’s surface and support life indirectly by forming minerals and soils.