Spinellien

Spinellien is a mineral group belonging to the oxide class. The general chemical formula for spinels is AB2O4, where A represents a divalent cation and B represents a trivalent cation. The most common and well-known mineral in this group is spinel itself, with the formula MgAl2O4. Other common members include magnetite (Fe3O4), chromite (FeCr2O4), and hercynite (FeAl2O4).

Spinels typically crystallize in the isometric crystal system, often forming octahedral crystals. They are known for their hardness, generally ranging from 5.5 to 8 on the Mohs scale, and their relatively high specific gravity. Many spinels are transparent to opaque and can exhibit a wide range of colors due to the presence of various trace elements. For example, red spinels often contain chromium, while blue spinels may contain iron and cobalt.

The varied colors and durability of some spinel gemstones, such as red spinel which was historically often mistaken for ruby, have led to their use in jewelry. Industrially, certain spinels are important. Magnetite, for instance, is a significant iron ore and is also used in magnetic applications. Chromite is the primary ore of chromium, essential for stainless steel production.