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.^[1]

Silicon-oxygen double chain in the anions of amphibole minerals.

For example, the amphibole group consists of 15 or more mineral species, most of them with the general unit formula A
_xB
_yC
_14-3x-2ySi
₈O
₂₂(OH)
₂, where A is a trivalent cation such as Fe³⁺
or Al³⁺
, B is a divalent cation such as Fe²⁺
, Ca²⁺
, or Mg²⁺
, and C is an alkali metal cation such as Li⁺
, Na⁺
, or K⁺
. In all these minerals, the anions consist mainly of groups of four SiO
₄ tetrahedra connected by shared oxygen corners so as to form a double chain of fused six-member rings. In some of the species, aluminum Al³⁺
may replace some silicon atoms Si⁴⁺
in the backbone, with extra B or C cations to balance the charges.

List of groups

^{[citation needed]}

• Alunite group
• Amphibole group
• Aragonite group
• Arsenic minerals
• Blodite group
• Calcite group
• Cancrinite group
• Clay minerals group
• Descloizite group
• Dolomite group
• Epidote group
• Feldspar group
• Feldspathoid
• Garnet group
• Hematite group
• Humite group
• Ilmenite group
• Langbeinites
• Mica group
• Pyroxene group
• Rutile group
• Serpentine group
• Smectite group
• Sodalite group
• Spinel group
• Tetradymite group

See also

• Mineral
• Mineral variety