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Corundum is a crystalline form of aluminium oxide (Al 2 O 3) typically containing traces of iron, titanium, vanadium, and chromium. [ 3 ] [ 4 ] It is a rock -forming mineral . It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. [ 7 ]
Sapphire is one of the two gem-varieties of corundum, the other being ruby (defined as corundum in a shade of red). Although blue is the best-known sapphire color, it occurs in other colors, including gray and black, and also can be colorless.
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.
In 2017, Lotus Gemology published Hughes' book Ruby & Sapphire: A Gemologist's Guide, [7] covering the corundum gem species. [ 8 ] [ 9 ] In 2019, Tongji University created an exhibit centering on Lotus Gemology's photography. [ 10 ]
Cue tip chalk (invented in its modern form by straight rail billiard pro William A. Spinks and chemist William Hoskins in 1897) [14] [15] is made by crushing silica and the abrasive substance corundum or aloxite [15] (aluminium oxide), [16] [17] into a powder. [15]
Pages in category "Corundum gemstones" The following 7 pages are in this category, out of 7 total. This list may not reflect recent changes. B. Black Star sapphire; G.
The corundum is blue, or sapphire. Wet slab, 10 cm (3.9 in) wide. Emery, or corundite, is a dark granular rock used to make an abrasive powder. The rock largely consists of corundum (aluminium oxide), mixed with other minerals. Industrial emery may contain a variety of other minerals and synthetic compounds.
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]