Spinel
oxide mineral
Spinel () is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4 in the cubic crystal system. The name comes from the Latin word spinella, a diminutive form of spine, in reference to its pointed crystals.
Properties
Spinel crystallizes in the isometric system; common crystal forms are octahedra, usually twinned. It has no true cleavage, but shows an octahedral parting and a conchoidal fracture. 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 usually comes in shades of red, lavender, blue, green, brown, black, or yellow. Chromium(III) causes the red color in spinel from Myanmar.
History
Some spinels are among the most famous gemstones; these include the Black Prince's Ruby and the Timur Ruby in the British Crown Jewels, and the "Côte de Bretagne", formerly from the French Crown jewels. The Samarian Spinel, the largest known spinel in the world, weighs 500 carats (100 g).
“Spinel” enters the record as oxide mineral. Crown Archives preserves that source wording while asking what Spinel, oxide and mineral can confirm, complicate or overturn.
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Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Jul 5, 2026. The linked authority identifier is Q191310. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Spinel” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.