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Aluminium oxide (or aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formula Al 2 O 3. It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium oxide. It is commonly called alumina and may also be called aloxide, aloxite, or alundum in various forms and ...
The term "octahedral" is used somewhat loosely by chemists, focusing on the geometry of the bonds to the central atom and not considering differences among the ligands themselves. For example, [Co(NH 3 ) 6 ] 3+ , which is not octahedral in the mathematical sense due to the orientation of the N−H bonds, is referred to as octahedral.
The spinels are any of a class of minerals of general formulation AB 2 X 4 which crystallise in the cubic (isometric) crystal system, with the X anions (typically chalcogens, like oxygen and sulfur) arranged in a cubic close-packed lattice and the cations A and B occupying some or all of the octahedral and tetrahedral sites in the lattice.
Aluminates are often formulated as a combination of basic oxide and aluminium oxide, for example the formula of anhydrous sodium aluminate NaAlO 2 would be shown as Na 2 O·Al 2 O 3. A number of aluminate oxyanions are known: The simplest is the approximately tetrahedral AlO 5− 4 found in the compound Na 5 AlO 4, [2] framework AlO −
Corundum is the name for a structure prototype in inorganic solids, derived from the namesake polymorph of aluminum oxide (α-Al 2 O 3). [1] Other compounds, especially among the inorganic solids, exist in corundum structure, either in ambient or other conditions.
It has no true cleavage, but shows an octahedral parting and a conchoidal fracture. [8] Its hardness is 8, its specific gravity is 3.5–4.1, and it is transparent to opaque with a vitreous to dull luster. It may be colorless, but is usually various shades of red, lavender, blue, green, brown, black, or yellow. [9]
Ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapphires. Ruby is one of the traditional cardinal gems, alongside amethyst, sapphire, emerald, and diamond. [3]
Aluminium(I) oxide (Al 2 O) Aluminium(II) oxide ( AlO ) (aluminium monoxide) Aluminium(III) oxide (aluminium oxide), ( Al 2 O 3 ), the most common form of aluminium oxide, occurring on the surface of aluminium and also in crystalline form as corundum , sapphire , and ruby .