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The mineral spinel MgAl 2 O 4 has a normal spinel structure. In a normal spinel structure, the ions are in the following positions, where i, j, and k are arbitrary integers and δ, ε, and ζ are small real numbers (note that the unit cell can be chosen differently, giving different coordinates): [16]
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]
Co 3 O 4 adopts the normal spinel structure, with Co 2+ ions in tetrahedral interstices and Co 3+ ions in the octahedral interstices of the cubic close-packed lattice of oxide anions. [ 4 ] tetrahedral coordination geometry of Co(II)
The atomic arrangement of the spinel group is a commonly studied structure and characteristically has four closely packed oxygen atoms. The nickel atoms are organized corresponding to a "normal" spinel arrangement.
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 ...
Cuprospinel is a mineral.Cuprospinel is an inverse spinel with the chemical formula CuFe 2 O 4, where copper substitutes some of the iron cations in the structure. [4] [5] Its structure is similar to that of magnetite, Fe 3 O 4, yet with slightly different chemical and physical properties due to the presence of copper.
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 (3,078–3,213 °F). [6]
Mn 3 O 4 has the spinel structure, where the oxide ions are cubic close packed and the Mn II occupy tetrahedral sites and the Mn III octahedral sites. [3] The structure is distorted due to the Jahn–Teller effect. [3]