Mineral group


In geology and mineralogy, a mineral group is a set of mineral species with essentially the same crystal structure and composed of chemically similar elements.

For example, the amphibole group consists of 15 or more mineral species, most of them with the general unit formula, where A is a trivalent cation such as or, B is a divalent cation such as,, or, and C is an alkali metal cation such as,, or. In all these minerals, the anions consist mainly of groups of four tetrahedra connected by shared oxygen corners so as to form a double chain of fused six-member rings. In some of the species, aluminum may replace some silicon atoms in the backbone, with extra B or C cations to balance the charges.

List of groups