geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

and

mineralogy Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proces ...

, a mineral group is a set of mineral species with essentially the same crystal structure and composed of chemically similar elements.Stuart J. Mills, Frédéric Hatert, Ernest H. Nickel, and Giovanni Ferraris (2009): "The standardisation of mineral group hierarchies: application to recent nomenclature proposals". ''European Journal of Mineralogy'', volume 21, number 5, pages 1073-1080. Tremolite-chain

For example, the

amphibole Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is A ...

group consists of 15 or more mineral species, most of them with the general unit formula , where A is a

trivalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Description The combining capacity, or affinity of an ...

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

such as or , B is a divalent cation such as , , or , and C is an

alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...

cation such as , , or . In all these minerals, the anions consist mainly of groups of four tetrahedra connected by shared

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

corners so as to form a double chain of fused six-member rings. In some of the species,

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...

may replace some

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...

atoms in the backbone, with extra B or C cations to balance the charges.

List of groups

Alunite group Alunite is a hydroxylated aluminium potassium sulfate mineral, formula K Al3( S O4)2(O H)6. It was first observed in the 15th century at Tolfa, near Rome, where it was mined for the manufacture of alum. First called ''aluminilite'' by J.C. De ...

Amphibole group Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is A ...

* Aragonite group *

Arsenic minerals The arsenic minerals or arsenic group are a group of trigonal symmetry minerals composed of arsenic-like elements, and one alloy. The elements are arsenic, antimony and bismuth Bismuth is a chemical element with the symbol Bi and atomic nu ...

* Blodite group * Calcite group *

Cancrinite group Cancrinite is a complex carbonate and silicate of sodium, calcium and aluminium with the formula sodium, Na6calcium, Ca2 carbon, Coxygen, O3)2, aluminum, Al6silicon, Si6O24�2water, H2O. It is classed as a member of the feldspathoid group of mi ...

Clay minerals group Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

* Descloizite group *

Dolomite group Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

Epidote group Epidote is a calcium aluminium iron sorosilicate mineral. Description Well developed crystals of epidote, Ca2Al2(Fe3+;Al)(SiO4)(Si2O7)O(OH), crystallizing in the monoclinic system, are of frequent occurrence: they are commonly prismatic in habi ...

Feldspar group Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldspa ...

Feldspathoid The feldspathoids are a group of tectosilicate minerals which resemble feldspars but have a different structure and much lower silica content. They occur in rare and unusual types of igneous rocks, and are usually not found in rocks containing prim ...

Garnet group Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different spe ...

* Hematite group *

Humite group Humite is a mineral found in the volcanically ejected masses of Vesuvius Mount Vesuvius ( ; it, Vesuvio ; nap, 'O Vesuvio , also or ; la, Vesuvius , also , or ) is a somma-stratovolcano located on the Gulf of Naples in Campania, Ital ...

* Ilmenite group *

Langbeinites Langbeinites are a family of crystalline substances based on the structure of langbeinite with general formula , where M is a large univalent cation (such as potassium, rubidium, caesium, or ammonium), and M' is a small divalent cation (for examp ...

Mica group Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect Cleavage (crystal), basa ...

Pyroxene group The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) ...

* Rutile group * Serpentine group *

Smectite group A smectite (from ancient Greek ''σμηκτός'' smektos 'lubricated'; ''σμηκτρίς'' smektris 'walker's earth', 'fuller's earth'; rubbing earth; earth that has the property of cleaning) is a mineral mixtures of various swelling sheet sil ...

Sodalite group Sodalite ( ) is a tectosilicate mineral with the formula , with royal blue varieties widely used as an ornamental gemstone. Although massive sodalite samples are opaque, crystals are usually transparent to translucent. Sodalite is a member of t ...

Spinel group The spinels are any of a class of minerals of general formulation which crystallise in the cubic (isometric) crystal system, with the X anions (typically chalcogens, like oxygen and sulfur) arranged in a cubic close-packed lattice and the cation ...

Tetradymite group Tetradymite is a mineral consisting of bismuth, tellurium and sulfide, Bi2 Te2 S, also known as telluric bismuth. If sulfur is absent the mineral is tellurobismuthite and the formula is then Bi2Te3. Traces of selenium are usually present. Crysta ...

References

{{mineral-stub *

List of groups

See also

References