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Inverse spinel structures have a different cation distribution in that all of the A cations and half of the B cations occupy octahedral sites, while the other half of the B cations occupy tetrahedral sites. 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.
Filipstadite is a very rare mineral [4] of the spinel group, with the formula (Mn,Mg)(Sb 5+ 0.5 Fe 3 + 0.5)O 4. [5] It is isometric, [3] although it was previously thought to be orthorhombic. When compared to a typical spinel, both the octahedral and tetrahedral sites are split due to cation ordering. [3] Filipstadite is chemically close to ...
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.
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]
The mineral ceylonite has the chemical composition of (Mg, Fe 2+) Al 2 O 4, putting it into a group of minerals known as the spinel group, or the oxide spinels. The oxide spinels have a formula of the model [A][B] 2 O 4; where [A] is commonly Fe 2+, Mg 2+, or Mn 2+, and [B] is Fe 3+, Al 3+, or Cr 3+. It is an iron-rich variety of the spinel ...
Spinel gemstones (1 C, 6 P) Pages in category "Spinel group" The following 19 pages are in this category, out of 19 total. This list may not reflect recent changes. ...
2, where A is a trivalent cation such as Fe 3+ or Al 3+, B is a divalent cation such as Fe 2+, Ca 2+, or Mg 2+, and C is an alkali metal cation such as Li +, Na +, or K +. In all these minerals, the anions consist mainly of groups of four SiO 4 tetrahedra connected by shared oxygen corners so as to form
In 1838, in the inventory of crown items, the stone under the cross was called a “large ruby”, and in the inventory of 1865 it was already listed as “an irregularly shaped spinel ruby, worth 100,000 rubles”. [15] Since 1967, the crown, and along with it the historical spinel, has been an exhibit of the Diamond Fund.