Ca2AlFe3Si3O12OH

Ca2AlFe3Si3O12OH is a mineral belonging to the garnet supergroup. Its chemical formula indicates the presence of calcium, aluminum, iron, silicon, oxygen, and hydroxyl groups. This specific composition places it within the hydrogarnet series, characterized by the presence of hydroxyl (OH) ions substituting for oxygen in the crystal structure. The structure is cubic, typical of garnets, with a complex arrangement of silicate tetrahedra and polyhedral sites occupied by the cations. The iron content is significant, distinguishing it from many other common garnets which are primarily aluminum silicates. Ca2AlFe3Si3O12OH is often found in metamorphic rocks, particularly those that have undergone high-pressure and moderate-temperature conditions. Its formation is associated with metasomatic processes and changes in the chemical environment of existing rock formations. While not as commonly encountered as some other garnets, it is of interest to mineralogists for understanding the variations within the garnet group and the geological conditions under which such minerals form. Its optical properties, such as color and refractive index, are influenced by its chemical composition, particularly the iron content.