Aluminum content distribution

Aluminum is the most abundant metal element in the Earth's crust, with a content of 8.3%, second only to oxygen and silicon. Its reserves rank second among metals. Among the metal varieties, it is the second largest Metalloid after steel. It mainly exists in aluminosilicate ores, as well as Bauxite and Cryolite. Aluminum oxide is a white amorphous powder that comes in various variants, among which the most familiar is α－ Al2O3 and β－ Al2O3. Corundum, which exists in nature, belongs to α- Al2O3, second only to diamond in hardness, has a high melting point and is resistant to acid and alkali. It is commonly used to make some bearings, abrasives, and refractory materials. Like a corundum crucible, it can withstand high temperatures of 1800 ℃. Al2O3 has multiple colors due to its inclusion of different impurities. For example, those containing trace Cr (III) are red, called Ruby; Sapphires containing Fe (II), Fe (III), or Ti (IV) are called sapphires