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Polyhedral representation of spinel MgAl 2 O 4. Spinel (/ s p ɪ ˈ n ɛ l, ˈ s p ɪ n əl / [7]) is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula MgAl 2 O 4 in the cubic crystal system. Its name comes from the Latin word spinella, a diminutive form of spine, in reference to its pointed crystals. [5]
[4] [5] As such, it is the only gemstone to have been initially identified from a faceted stone. Most pieces of the gem, prior to Taaffe, had been misidentified as spinel . For many years afterwards, it was known only in a few samples, and it is still one of the rarest gemstone minerals in the world.
An example of an inverse spinel is Fe 3 O 4, if the Fe 2+ (A 2+) ions are d 6 high-spin and the Fe 3+ (B 3+) ions are d 5 high-spin. In addition, intermediate cases exist where the cation distribution can be described as (A 1− x B x )[A x ⁄ 2 B 1− x ⁄ 2 ] 2 O 4 , where parentheses () and brackets [] are used to denote tetrahedral and ...
The gemstone at the front of the Imperial State Crown. The Black Prince's Ruby is a large, irregular cabochon red spinel weighing 170 carats (34 g) set in the cross pattée above the Cullinan II diamond at the front of the Imperial State Crown of the United Kingdom. [1]
Samarian Spinel, the world's largest spinel; Menshikov Ruby, the world's second largest spinel set on top of the Great Imperial Crown of Russia; Timur Ruby, believed to be a ruby until 1851, hence its name; Black Prince's Ruby, the famous spinel mounted on the Imperial State Crown of the United Kingdom
[2] [3] Hercynite is a spinel of regular symmetry and normal cation distribution, but some disorder occurs in its structure. It consists of ferrous (Fe 2+) ions and aluminium ions (Al 3+); however some ferric ions (Fe 3+) may be located in the structure of hercynite. [5] Melting point of this mineral is inbetween 1,692–1,767 °C (3,078 ...
Today's Wordle answer on Monday, December 2, 2024, is GUILE. How'd you do? Next: Catch up on other Wordle answers from this week. Show comments. Advertisement. Advertisement. Holiday Shopping Guides.
Trevorite is a rare nickel iron oxide mineral belonging to the spinel group.It has the chemical formula NiFe 3+ 2 O 4.It is a black mineral with the typical spinel properties of crystallising in the cubic system, black streaked, infusible and insoluble in most acids.