Silicate minerals
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The silicate minerals make up the largest and most important class of rock-forming minerals, comprising approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group. Silicate minerals all contain silicon and oxygen.
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[edit] Nesosilicates or isosilicates
Nesosilicates, or orthosilicates, have isolated [SiO4]4− tetrahedra that are connected only by interstitial cations.
- Phenacite group
- Olivine group
- Forsterite - Mg2SiO4
- Fayalite - Fe2SiO4
- Garnet group
- Pyrope - Mg3Al2(SiO4)3
- Almandine - Fe3Al2(SiO4)3
- Spessartine - Mn3Al2(SiO4)3
- Grossular - Ca3Al2(SiO4)3
- Andradite - Ca3Fe2(SiO4)3
- Uvarovite - Ca3Cr2(SiO4)3
- Hydrogrossular - Ca3Al2Si2O8(SiO4)1-m(OH)4m
- Zircon group
- Al2SiO5 group
- Andalusite - Al2SiO5
- Kyanite - Al2SiO5
- Sillimanite - Al2SiO5
- Dumortierite - Al6.5-7BO3(SiO4)3(O,OH)3
- Topaz - Al2SiO4(F,OH)2
- Staurolite - Fe2Al9(SiO4)4(O,OH)2
- Humite group - (Mg,Fe)7(SiO4)3(F,OH)2
- Norbergite - Mg3(SiO4)(F,OH)2
- Chondrodite - Mg5(SiO4)(F,OH)2
- Humite - Mg7(SiO4)(F,OH)2
- Clinohumite - Mg9(SiO4)(F,OH)2
- Datolite - CaBSiO4(OH)
- Titanite - CaTiSiO5
- Chloritoid - (Fe,Mg,Mn)2Al4Si2O10(OH)4
[edit] Sorosilicates
Sorosilicates have isolated double tetrahedra groups with (Si2O7)6− or a ratio of 2:7.
- Hemimorphite (calamine) - Zn4(Si2O7)(OH)2·H2O
- Lawsonite - CaAl2(Si2O7)(OH)2·H2O
- Ilvaite - CaFe2+2Fe3+O(Si2O7)(OH)
- Epidote group (has both (SiO4)4− and (Si2O7)6− groups)
- Epidote - Ca2(Al,Fe)3O(SiO4)(Si2O7)(OH)
- Zoisite - Ca2Al3O(SiO4)(Si2O7)(OH)
- Clinozoisite - Ca2Al3O(SiO4)(Si2O7)(OH)
- Tanzanite - Ca2Al3O(SiO4)(Si2O7)(OH)
- Allanite - Ca(Ce,La,Y,Ca)Al2(Fe2+,Fe3+)O(SiO4)(Si2O7)(OH)
- Vesuvianite (idocrase) - Ca10(Mg,Fe)2Al4(SiO4)5(Si2O7)2(OH)4
[edit] Cyclosilicates
Cyclosilicates, or ring silicates, have linked tetrahedra with (SixO3x)2x- or a ratio of 1:3. These exists as 3-member (Si3O9)6-, 4-member (Si4O12)8- and 6-member (Si6O18)12- rings.
- 3-member ring
- Benitoite - BaTi(Si3O9)
- 4-member ring
- Axinite - (Ca,Fe,Mn)3Al2(BO3)(Si4O12)(OH)
- 6-member ring
- Beryl/Emerald - Be3Al2(Si6O18)
- Cordierite - (Mg,Fe)2Al3(Si5AlO18)
- Tourmaline - (Na,Ca)(Al,Li,Mg)3-(Al,Fe,Mn)6(Si6O18)(BO3)3(OH)4
[edit] Inosilicates
Inosilicates, or chain silicates, have interlocking chains of silicate tetrahedra with either SiO3, 1:3 ratio, for single chains or Si4O11, 4:11 ratio, for double chains.
[edit] Single chain inosilicates
- Pyroxene group
- Enstatite - orthoferrosilite series
- Enstatite - MgSiO3
- Ferrosilite - FeSiO3
- Pigeonite - Ca0.25(Mg,Fe)1.75Si2O6
- Diopside - hedenbergite series
- Diopside - CaMgSi2O6
- Hedenbergite - CaFeSi2O6
- Augite - (Ca,Na)(Mg,Fe,Al)(Si,Al)2O6
- Sodium pyroxene series
- Spodumene - LiAlSi2O6
- Enstatite - orthoferrosilite series
- Pyroxenoid group
- Wollastonite - CaSiO3
- Rhodonite - MnSiO3
- Pectolite - NaCa2(Si3O8)(OH)
[edit] Double chain inosilicates
- Amphibole group
- Anthophyllite - (Mg,Fe)7Si8O22(OH)2
- Cumingtonite series
- Cummingtonite - Fe2Mg5Si8O22(OH)2
- Grunerite - Fe7Si8O22(OH)2
- Tremolite series
- Tremolite - Ca2Mg5Si8O22(OH)2
- Actinolite - Ca2(Mg,Fe)5Si8O22(OH)2
- Hornblende - (Ca,Na)2-3(Mg,Fe,Al)5Si6(Al,Si)2O22(OH)2
- Sodium amphibole group
- Glaucophane - Na2Mg3Al2Si8O22(OH)
- Riebeckite (asbestos) - Na2Fe2+3Fe3+2Si8O22(OH)2
- Arfvedsonite - Na3(Fe,Mg)4FeSi8O22(OH)2
[edit] Phyllosilicates
Phyllosilicates (from Greek φύλλον phyllon, leaf), or sheet silicates, form parallel sheets of silicate tetrahedra with Si2O5 or a 2:5 ratio.
- Serpentine group
- Antigorite - Mg3Si2O5(OH)4
- Chrysotile - Mg3Si2O5(OH)4
- Lizardite - Mg3Si2O5(OH)4
- Clay mineral group
- Kaolinite - Al2Si2O5(OH)4
- Illite - (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)]
- Smectite -
- Montmorillonite - (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O
- Vermiculite - (MgFe,Al)3(Al,Si)4O10(OH)2·4H2O
- Talc - Mg3Si4O10(OH)2
- Palygorskite - (Mg,Al)2Si4O10(OH)·4(H2O)
- Pyrophyllite - Al2Si4O10(OH)2
- Mica group
- Biotite - K(Mg,Fe)3(AlSi3O10)(OH)2
- Muscovite - KAl2(AlSi3O10)(OH)2
- Phlogopite - KMg3Si4O10(OH)2
- Lepidolite - K(Li,Al)2-3(AlSi3O10)(OH)2
- Margarite - CaAl2(Al2Si2O10)(OH)2
- Glauconite - (K,Na)(Al,Mg,Fe)2(Si,Al)4O10(OH)2
- Chlorite group
- Chlorite - (Mg,Fe)3(Si,Al)4O10(OH)2•(Mg,Fe)3(OH)6
[edit] Tectosilicates
Tectosilicates, or "framework silicates", have a three-dimensional framework of silicate tetrahedra with SiO2 or a 1:2 ratio. This group comprises nearly 75% of the crust of the Earth. Tectosilicates, with the exception of the quartz group, are aluminosilicates.
- Quartz group
- Quartz - SiO2
- Tridymite - SiO2
- Cristobalite - SiO2
- Feldspar group
- Alkali-feldspars
- Potassium-feldspars
- Microcline - KAlSi3O8
- Orthoclase - KAlSi3O8
- Sanidine - KAlSi3O8
- Anorthoclase - (Na,K)AlSi3O8
- Albite - NaAlSi3O8
- Potassium-feldspars
- Plagioclase feldspars
- Albite - NaAlSi3O8
- Oligoclase - (Na,Ca)(Si,Al)4O8 (Na:Ca 4:1)
- Andesine - (Na,Ca)(Si,Al)4O8 (Na:Ca 3:2)
- Labradorite - (Na,Ca)(Si,Al)4O8 (Na:Ca 2:3)
- Bytownite - (Na,Ca)(Si,Al)4O8 (Na:Ca 1:4)
- Anorthite - CaAl2Si2O8
- Alkali-feldspars
- Feldspathoid group
- Petalite - LiAlSi4O10
- Scapolite group
- Analcime - NaAlSi2O6•H2O
- Zeolite group
- Natrolite - Na2Al2Si3O10•2H2O
- Chabazite - CaAl2Si4O12•6H2O
- Heulandite - CaAl2Si7O18•6H2O
- Stilbite - NaCa2Al5Si13O36•17H2O
[edit] References
- Deer, W.A.; Howie, R.A., & Zussman, J. (1992). An introduction to the rock forming minerals (2nd edition ed.). London: Longman.
- Deer, W.A.; Howie, R.A., Wise, W.S. & Zussman, J. (2004). Rock-forming minerals. Volume 4B. Framework silicates: silica minerals. Feldspathoids and the zeolites (2nd edition ed.). London: Geological Society of London. p. 982 pp.
- Hurlbut, Cornelius S. (1966). Dana's Manual of Mineralogy (17th edition ed.). ISBN ISBN 0-471-03288-3.
- Hurlbut, Cornelius S.; Klein, Cornelis (1985). Manual of Mineralogy (20th edition ed.). ISBN ISBN 0-471-80580-7.
