Halogenidit

Halogenidit, or halogenides, are chemical compounds in which a halogen element (fluorine, chlorine, bromine or iodine) is bonded to another element, commonly a metal. In mineralogical contexts the term often refers to a class of minerals known as halide minerals, where the dominant anion is a halide ion (Cl−, F−, Br−, or I−).

Halide minerals include examples such as halite (sodium chloride, NaCl), sylvite (potassium chloride, KCl), and carnallite (KMgCl3·6H2O), as well as fluorite (calcium fluoride, CaF2) and cryolite (sodium hexafluoroaluminate, Na3AlF6). These compounds are typically ionic and form under conditions where halogen-rich fluids interact with metals or metalloids. The halogenide group encompasses a wide range of compositions, from simple binary systems to more complex hydrated salts.

Occurrence and formation commonly involve evaporitic environments, saline brines, or hydrothermal settings where halogens are concentrated. Halide minerals are economically important; halite is a major source of sodium chloride (table salt), sylvite and carnallite are important potassium and potassium-magnesium salts, and fluorite serves as a flux in mining and as a pigment. Cryolite historically played a role in aluminum production.

Properties of halogenides vary, but they are typically relatively soft minerals with moderate to low hardness, and their structures reflect the strong ionic bonding of halide ions with metal cations. In chemistry more broadly, halogenides also include many metal halides and organic halides used across industry and research.

See also: halide minerals, halogen elements, ionic compounds.