Biotite

Description

Biotite serves as a designated group of phyllosilicate minerals belonging to the broader mica family. Chemically, it exists as a solid-solution series characterized by the approximate formula K(Mg,Fe)3AlSi3O10(F,OH)2, ranging between the magnesium-dominant phlogopite and the iron-dominant annite. While the International Mineralogical Association reclassified biotite as a mineral group rather than a single species in 1998, the term remains a standard nomenclature for identifying dark-colored micas in geological and ceramic contexts. In ceramic applications, its presence in raw materials or clay bodies introduces iron and magnesium, which can significantly influence fluxing behavior, glaze color, and maturation temperatures during firing. It is characterized by its distinct layered crystal structure, a hallmark of the phyllosilicate group.