Encyclopedia of Global Resources part 98 provides a wide variety of perspectives on both traditional and more recent views of Earth's resources. It serves as a bridge connecting the domains of resource exploitation, environmentalism, geology, and biology, and it explains their interrelationships in terms that students and other nonspecialists can understand. The articles in this set are extremely diverse, with articles covering soil, fisheries, forests, aluminum, the Industrial Revolution, the . Department of the Interior, the hydrologic cycle, glass, and placer mineral deposits. . | 898 Oxygen Global Resources According to their chemical compositions there are seven types of oxides A2O AO A2O3 ABO3 AB2O4 AO2 and AmBnO2 m n where A and B are metals and m and n are integers. Cuprite CuO2 an important ore of copper belongs to type A2O. Both periclase MgO and tenorite CuO belong to type AO. Corundum Al2O3 hematite and ilmenite belong to type A2O3. Corundum can be utilized as an abrasive and a gemstone. Hematite is an important ore of iron. Ilmenite is an ore of titanium. Perovskite CaTiO3 belongs to type ABO3. Spinel chrysoberyl and gahnite ZnAl2O4 belong to type AB2O4. Pyrolusite cassiterite and rutile TiO2 belong to type AO2. Pyrolusite is an ore of manganese. Cassiterite is an important source of tin. Rutile is an ore of titanium. Columbite-tantalite 4 Fe Mn Nb Ta 2O6 belongs to type AmBnO2 m n . Besides chemical compositions the structural optical and physical properties of oxides are studied. Structural information can be revealed by X-ray diffraction. Optical properties include color appearance reflection and transmission. Physical properties include density mechanical strength and thermal capacitance. Some of the oxides are distributed throughout the world while others are limited to a few regions. For example magnetite can be found in the United States hematite can be found in the United States Venezuela Brazil Canada and Australia and cassiterite can be found in Malaysia Bolivia and other countries. Xingwu Wang See also Aluminum Beryllium Copper Igneous processes rocks and mineral deposits Iron Manganese Oxygen Pegmatites Quartz Sand and gravel Silicon Tin Titanium. Oxygen Category Mineral and other nonliving resources Where Found Oxygen is the most abundant element in the Earth s crust percent by weight occurring mainly as oxides and silicates of metals. The earth s waters are percent oxygen by weight and the atmosphere is percent oxygen. The combined weight of oxygen in the crust hydrosphere and atmosphere is about 50 .
