Mica CAS#: ChemicalBook
The general term designates all ferromagnesium micas, also called black mica or magnesiumiron mica. This black and platelike mineral is found in some igneous rocks, such as granite. It is tetrahedral mica with aluminum substituted for silicon in the tetrahedral sheet, and ferrous (Fe 2+) or magnesium (Mg 2+)io ns in the octahedral sheet.