Mineral groups

Minerals can be classified into distinct groups based upon similar atomic structure and/or chemical composition.

What is a mineral?

A mineral is a naturally-occurring inorganic solid with a specific chemical composition and a characteristic regular, geometric arrangement of its constituent atoms. Minerals can be classified into distinct groups based upon similar atomic structure and/or chemical composition (which is mainly based on their anions).

Many minerals contain elements that can be freely exchanged with other elements of similar properties. This is called ionic substitution. These elements can occur as either major elements in the mineral structure, or as trace elements in tiny amounts. (e.g. the mineral sphalerite (Zn, Fe)S can contain highly variable concentrations of both Zn (zinc) and Fe (iron) and also commonly contains trace amounts of Cd (cadmium).

Silicates are minerals with silicon and oxygen linked together as a major component, and can be classified according to the way in which other atoms present are linked to these silicon and oxygen atoms.

Main mineral groups

Minerals are listed in groups by mineral name, chemical composition and crystal system. Species marked * are more common within each group.

Native Elements and Alloys

  • Copper* Cu (cub)
  • Silver* Ag (cub)
  • Gold* Au (cub)
  • Mercury Hg (hex)
  • Iron Fe (cub)
  • Nickel-iron alloy (Ni, Fe) (cub)
  • Platinum Pt (cub)
  • Diamond C (cub)
  • Graphite* C (hex)
  • Sulfur* S (orth)
  • Arsenic As (hex)
  • Antimony Sb (hex)
  • Bismuth* Bi (hex)

Sulfides (also includes Selenides, Tellurides, Bismuthinides and Antimonides)

  • Pyrite* FeS2 (cub)
  • Marcasite* FeS2 (orth)
  • Pyrrhotite* Fe1-XS (hex)
  • Arsenopyrite* FeAsS (mon)
  • Chalcopyrite* CuFeS2(tet)
  • Chalcocite Cu2S (orth)
  • Bornite Cu5FeS4(cub)
  • Covellite CuS (hex)
  • Galena* PbS (cub)
  • Sphalerite* (Zn,Fe)S (cub)
  • Pentlandite* (Fe, Ni)9S8(cub)
  • Millerite* NiS (hex)
  • Molybdenite* MoS2(hex)
  • Stibnite* Sb2S3(orth)
  • Bismuthinite* Bi2S3(orth)
  • Cinnabar HgS (hex)
  • Realgar AsS (mon)
  • Orpiment As2S3(mon)
  • Acanthite Ag2S (mon)

Sulfosalts

  • Bournonite PbCuSbS3(orth)
  • Pyrargyrite Ag3SbS3(hex)
  • Tetrahedrite* (Cu,Fe,Ag,Zn)12Sb4S13(cub)

Oxides

  • Cuprite Cu2O (cub)
  • Magnetite* Fe3O4(cub)
  • Spinel* MgAl2O4(cub)
  • Hematite* Fe2O3(hex)
  • Iimenite* FeTiO3(hex)
  • Rutile* TiO2(tet)
  • Cassiterite* SnO2(tet)
  • Chromite* FeCr2O4(cub)
  • Pyrolusite* MnO2(tet)
  • Hausmannite Mn3O4(tet)
  • Cryptomelane K(Mn4+, Mn2+)8O16(mon)
  • Corundum* Al2O3(hex)
  • Uraninite* UO2(cub)
  • Columbite-Tantalite Group (Fe, Mn)(Nb,Ta)O6(orth)

Hydroxides

  • Brucite Mg(OH)2(hex)
  • Goethite* FeO(OH) (orth)
  • Manganite* MnO(OH) (mon)

Halides

  • Halite* NaCl (cub)
  • Sylvite* KCl (cub)
  • Fluorite* CaF2(cub)

Carbonates

  • Calcite* CaCO3(hex)
  • Aragonite* CaCO3(orth)
  • Dolomite* CaMg(CO3)2(hex)
  • Siderite* FeCO3(hex)
  • Magnesite* MgCO3(hex)
  • Rhodochrosite MnCO3(hex)
  • Smithsonite* ZnCO3(hex)
  • Cerussite* PbCO3(orth)
  • Azurite* Cu3(CO3)2(OH)2(mon)
  • Malachite* Cu2(CO3)(OH)2(mon)

Nitrates - uncommon

  • Niter KNO3

Iodates - rare

Borates

  • Borax Na2B4O7.10H2O(mon)
  • Ulexite NaCaB5O9.8H2O(tric)
  • Colemanite Ca2B6O11.5H2O(mon)

Sulfates

  • Gypsum* CaSO4.2H2O(mon)
  • Anhydrite CaSO4(orth)
  • Barite* BaSO4(orth)
  • Anglesite* PbSO4(orth)
  • Glauberite Na2Ca(SO4)2 (mon)
  • Celestite SrSO4(orth)
  • Chalcanthite* CuSO4.5H2O(tric)
  • Epsomite MgSO4.7H2O(orth)
  • Alunite K2Al6(SO4)4(OH)12(hex)
  • Jarosite* (K,Ag,NH4, H3O1+, Na)2Fe6(SO4)4OH12(hex)
  • Copiapite Fe2+Fe3+4(SO4)6(OH)2.2OH2O(tric)
  • Halotrichite Fe2+Al2(SO4)4.22H2O(mon)
  • Melanterite Fe2+SO4.7H2O(mon)

Chromates

  • Crocoite PbCrO4(mon)

Phosphates

  • Apatite* (Ca,Sr,Pb,Na,K)(PO4)3(F,Cl,OH) (hex)
  • Monazite* (Ce,La,Nd,Th)PO4(mon)
  • Pyromorphite* Pb5(PO4)3Cl (hex)
  • Variscite AlPO4.2H2O(orth)
  • Vivianite Fe3(PO4)2.8H2O(mon)
  • Wavellite* Al3(PO4) 2 (OH)3.5H2O(orth)
  • Turquoise CuAl6(PO4)4(OH)8.5H2O(tric)
  • Torbernite Cu(UO2)2(PO4)2.8-12H2O(tet)
  • Autunite Ca(UO2)2(PO4)2.10-12H2O(tet)

Arsenates

  • Scorodite FeAsO4.2H2O(orth)
  • Mimetite Pb5(AsO4)3Cl (mon)
  • Olivenite Cu2(AsO4)(OH) (orth)
  • Adamite Zn2(AsO4)(OH) (orth)

Antimonates - uncommon

  • Bindheimite Pb2Sb2O6(O,OH) (cub)

Vanadates

  • Vanadinite Pb5(VO4)3Cl (hex)
  • Descloisite PbZn(VO4)(OH) (orth)

Molybdates and Tungstates

  • Scheelite* CaWO4(tet)
  • Wolframite* (Fe,Mn)WO4(mon)
  • Wulfenite PbMoO4(tet)

Organic Compounds

  • Whewellite CaC2O4.H2O(calcium oxalate) (mon)

Silicates

Silicates include:

Quartz Group * (all SiO2)

Varieties: common crystalline quartz (hex); colourless (rock crystal); white (milky quartz: caused by inclusions of liquid and gas); brown to black (smoky quartz: caused by exposure to natural radioactivity); yellow to orange (citrine: caused by tiny inclusions of iron hydroxides); purple (amethyst: caused by trace amounts of Fe3+); pink (rose quartz: caused by trace amounts of Mn and/or Ti); also blue (caused by microscopic inclusions of rutile or tourmaline) and green (caused by inclusions of Cr-rich micas or chlorite).

  • Rutilated quartz is quartz with inclusions of rutile needles.
  • Tridymite (mon)
  • Cristobalite (cub or tet)
  • Microcrystalline and cryptocrystalline silica: agate, jasper, chalcedony, tiger eye, chrysoprase, prase, onyx, flint, chert
  • Opal is hydrous silica: SiO2.nH2O. Varieties include black, white, boulder, crystal, volcanic, wood opal and hyalite.
Olivine Group *

General formula is (Mg,Fe,Mn,Ni)2SiO4(orth)

Most common end-members are forsterite Mg2SiO4and fayalite Fe2SiO4

Pyroxene Group *

General formula is ABZ2O6

Where: A = (Ca, Fe2+, Li, Mg, Mn2+, Na, Zn); B = (Al, Cr3+, Fe2+, Fe3+, Mg, Mn2+, Sc, Ti, V3+) and Z = (Al, Si)

Most common members are:

  • Diopside CaMgSi2O6(mon)
  • Augite (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6(mon)
  • Enstatite Mg2Si2O6(orth)
  • Hedenbergite CaFe2+Si2O6(mon)
Amphibole Group *

General formula is: AB2C5T8O22X2

Where A = (Na,K); B = (Ca,Na,Fe,Mg,Mn,Li,Zn,Ni,Co)

C = (Mg,Fe,Al,Ti Mn,Cr,Li,Zr Zn,Ni,Co)

T = (Si,Al,Ti)

X = (OH,F,Cl,O)

Most common members are:

  • Actinolite Ca2(Mg,Fe)5Si8O22(OH)2(mon)
  • Ferrohornblende Ca2Fe2+4(Al,Fe3+)Si7AlO22(OH)2(mon)
  • Pargasite NaCa2(Mg4Al)Si6Al2O22(OH)2(mon)
  • Tremolite Ca2Mg5Si8O22(OH)2(mon)
Feldspar group *

General Formula is XZ4O8 Where: X = (Ba,Ca,K,Na,NH4,Sr) and Z = (Al,B,Si)

Most common members are:

  • Albite NaAlSi3O8(tric)
  • Anorthite CaAl2Si2O8(tric)
  • Microcline KAlSi3O8(tric)
  • Orthoclase KAlSi3O8(mon)
Garnet group *

General formula is: A3B2(SiO4)3

Where: A = (Ca,Fe2+, Mg, Mn2+) and B = (Al,Cr3+, Fe3+, Mn3+,Si,Ti,V3+,Zr)

Common members are:

  • Almandine Fe3Al2(SiO4)3(cub)
  • Andradite Ca3Fe2(SiO4)3(cub)
  • Grossular Ca3Al2(SiO4)3(cub)
  • Pyrope Mg3Al2(SiO4)3(cub)
  • Spessartine Mn3Al2(SiO4)3(cub)
  • Uvarovite Ca3Cr2(Si04)3(cub)
Mica group *

These have a general formula of: IM2-3T4O10A2

Where: I = (K, Na,Ca,Cs,NH4,Rb,Ba); M = (Li,Fe2+,Fe3+,Mg,Al,Ti,Mn2+,Mn3+,Zn,Cr,V);

T = (Al, Fe3+,Si,Be,B); A = (F,OH,Cl,O)

Most common members are:

  • Annite KFe3AlSi3O10(OH)2(mon)
  • Muscovite KAl2AlSi3O10(OH)2(mon)
  • Phlogopite KMg3AlSi3O10(OH)2(mon)
Tourmaline group

General formula is: WX3Y6(BO3)3Si6018(O,OH,F)4

Where: W = (Ca,K,Na); X = (Al,Fe2+,Fe3+, Li,Mg,Mn2+); and Y = (Al,Cr3+,Fe3+,V3+)

Common members are:

  • Dravite NaMg3Al6(BO3)3Si6O18(OH)4(hex)
  • Elbaite Na(Li,Al)3Al6(BO3)3Si6O18(OH)4(hex)
  • Schorl NaFe2+3Al6(BO3)3Si6O186(OH)4(hex)
Zeolite group

A large group of generally hydrous alumino-silicates which contain open cavities in their structure.

Most common members are:

  • Analcime NaAlSi2O6.H2O(cub, tet, hex, orth, tric, mon)
  • Chabazite (Ca0.5,Na,K)4Al4Si8O24.12H2O(hex)
  • Heulandite (Ca0.5,Sr0.5,Ba0.5,Mg0.5,Na,K)Al9Si27O72.24H2O(mon)
  • Laumontite Ca4 Al8Si16O48.18H2O(mon)
  • Mesolite Na16Ca16Al48Si72O240.64H2O(orth)
  • Natrolite Na2Al2Si3O10.2H2O(orth)
  • Phillipsite (K,Na,Ca0.5,Ba0.5)4-7Al4-7Si12-9O32.12H2O(mon)
  • Stilbite (Ca0.5,Na,K)9Al9Si27O72.28H2O(mon)
  • Thomsonite Ca2NaAl5Si5O20.6H2O(orth)
Other common silicates
  • Zircon ZrSiO4(tet)
  • Epidote Ca2(Fe,Al)3(SiO4)3(OH) (mon)
  • Prehnite Ca2Al2Si3O10(OH)2(orth)
  • Sillimanite Al2SiO5(orth)
  • Andalusite Al2SiO5(orth)
  • Kyanite Al2SiO5(tric)
  • Cordierite Mg2Al4Si5018(orth)
  • Staurolite (Fe,Mg,Zn)2Al9Si4O23(OH) (orth)
  • Titanite (or sphene) CaTiSi05(mon)
  • Vesuvianite Ca10Mg2Al4(SiO4)5(Si2O7OH)4(tet)
  • Wollastonite CaSiO3 (tric)
  • Rhodonite (Mn,Fe,Mg)SiO3(tric)
  • Beryl Be3Al2Si6O18 (hex)
  • Topaz Al2SiO4(F,OH)2 (orth)
  • Clinochlore (Mg,Fe)5Al(Si3Al)O10(OH)8 (mon)
  • Axinite (Ca,Fe,Mg,Mn)3Al2BSi4O15(OH) (tric)
  • Kaolinite Al2Si2O5(OH)4(tric)
  • Dickite Al2Si2O5(OH)4 (mon)
  • Halloysite Al2Si2O5(OH)4 (mon)
  • Montmorillonite (Na,Ca)0.3(Al,Mg)2Si4O10(OH)2.nH2O(mon)
  • Nontronite Na0.3Fe3+2(Si, Al)4O10(OH)2.nH2O(mon)
  • Antigorite (Mg,Fe2+)3Si2O5(OH)4 (mon)
  • Clinochrysotile Mg3Si2O5(OH)4 (mon)
  • Lizardite Mg3Si2O5(OH)4 (trig, hex)
  • Willemite Zn2SiO4(hex)
  • Apophyllite KCa4 Si8O20(F,OH).8H2O(tet)
  • Talc Mg3Si4O10(OH)2(mon)


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