Biotite is a common rock-forming mineral that belongs to the MICA group of minerals. It is a black or dark-brown member of the MICA family and is known by its chemical formula K(Mg, Fe)3AlSi3O10(F, OH)2. Biotite is found in many igneous and metamorphic rocks, and is often associated with other MICA minerals such as muscovite and phlogopite. It is also used as an industrial mineral in the production of roofing shingles, insulation, and other products. The term 'MICA' is derived from the Latin word for 'CRUMB, ' which is fitting since biotite is composed of small flakes.