Of which aluminium oxide mineral are ruby and sapphire among the coloured varieties?
Aluminium oxide Aluminium oxide Aluminium oxide (IUPAC name) or aluminum oxide (American English) is a chemical compound of aluminium and oxygen with the chemical formula . It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium(III) oxide. It is commonly called alumina (regardless of whether the element is spelled aluminum or aluminium), and may also be called aloxide, aloxite, or alundum depending on particular forms or applications. It occurs naturally in its crystalline polymorphic phase α-AlO as the mineral corundum, varieties of which form the precious gemstones ruby and sapphire. AlO is significant in its use to
Aluminium oxide widely used in grinding operations, particularly cutoff tools. As the powdery abrasive mineral aloxite, it is a major component, along with silica, of the cue tip "chalk" used in billiards. Aluminium oxide powder is used in some CD/DVD polishing and scratch-repair kits. Its polishing qualities are also behind its use in toothpaste. Aluminium oxide flakes are used in paint for reflective decorative effects, such as in the automotive or cosmetic industries. Aluminium oxide has been used in a few experimental and commercial fiber materials for high-performance applications (e.g., Fiber FP, Nextel 610, Nextel 720). Alumina nanofibers in particular have become