Spinel

Overview Spinel is a mineral composed of Mg-Al oxides, as containing magnesium, iron, zinc, manganese, etc. elements, they can be divided into many forms, such as aluminum spinel, iron spinel, zinc spinel, manganese spinel, chrome spinel and so on. Due to the different elements, different spinel can have different colors, for example, magnesium spinel is between the red, blue, green, brown, and the colorless; zinc spinel is dark green and iron spinel is Black, etc. Spinel shows a hard glassy octahedral, granular and block. They can be founded in the igneous rock, granitic pegmatite and metamorphic limestone. Some transparent and beautiful spinel can be used as precious stones and some used as an iron-containing magnetic material. Now people have could produce more than 200 varieties of spinel. Spinel is a family mineral, formed by contact metamorphism in the molten magma when this magma intrusting into the impure limestone or dolomite. Some appear in the Al-rich basite magmatic rocks. Gem-quality spinel mainly refers to Mg-Al spinel, an Mg-Al oxide. Its form is the octahedron and the aggregation of octahedron and rhombic dodecahedron. They have varied colors, colorless, pink, red, purple, light purple, deep blue, blue, yellow, and brown and so on. Spinel is divided by its color variety; there is red, orange, blue-violet, blue spinel and so on. Pink and red spinel aglow red fluorescence when in the long and short-wave UV-wave. Physical Properties Spinel Chemical formula: MgAl2O4 Crystal system: isometric system Crystal Features: Octahedral crystal form, the aggregation of octahedron and rhombic dodecahedron Luster: vitreous luster and sub-adamantine luster Transparency: Transparent and opaque Refractive index: 1.718, it changes according to the content of trace elements; maximum is 2.000; no birefringence; no polychroism Special optical effects: Star effect, aventurescence and rarity Hardness: 8 Density: 3.60 (+0.10, -0.03) g / cm3 ItemAl2O3MgO%SiO2%Bodydensity g/cm3Porosity%Spinel%Silicate%Indicators56-6228-32<4.0<3.0<9.085-9010