Silicate minerals

The silicate minerals make up the largest and most important class of rock-forming minerals, constituting 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.

Nesosilicates or orthosilicates

Nesosilicates (from Greek νησος nēsos, island), or orthosilicates, have isolated (insular) [SiO₄]⁴⁻ tetrahedra that are connected only by interstitial cations.

• Phenacite group
  • Phenacite - Be₂SiO₄
  • Willemite - Zn₂SiO₄
• 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)_3-m(OH)_4m
• Zircon group
  • Zircon - ZrSiO₄
  • Thorite - (Th,U)SiO₄

Archivo:Kyanite crystals.jpg

Kyanite crystals (unknown scale)

• Al₂SiO₅ group
  • Andalusite - Al₂SiO₅
  • Kyanite - Al₂SiO₅
  • Sillimanite - Al₂SiO₅
  • Dumortierite - Al_6.5-7BO₃(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

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)
  • Dollaseite-(Ce) - CaCeMg₂AlSi₃O₁₁F(OH)
• Vesuvianite (idocrase) - Ca₁₀(Mg,Fe)₂Al₄(SiO₄)₅(Si₂O₇)₂(OH)₄

Cyclosilicates

Cyclosilicates, or ring silicates, have linked tetrahedra with (Si_xO_3x)^2x- or a ratio of 1:3. These exist 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

Inosilicates

Inosilicates (from Greek ις [genitive: ινος inos], fibre), 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.

Single chain inosilicates

• Pyroxene group
  • Enstatite - orthoferrosilite series
    • Enstatite - MgSiO₃
    • Ferrosilite - FeSiO₃
  • Pigeonite - Ca_0.25(Mg,Fe)_1.75Si₂O₆
  • Diopside - hedenbergite series
    • Diopside - CaMgSi₂O₆
    • Hedenbergite - CaFeSi₂O₆
    • Augite - (Ca,Na)(Mg,Fe,Al)(Si,Al)₂O₆
  • Sodium pyroxene series
    • Jadeite - NaAlSi₂O₆
    • Aegirine (Acmite) - NaFe³⁺Si₂O₆
  • Spodumene - LiAlSi₂O₆
• Pyroxenoid group
  • Wollastonite - CaSiO₃
  • Rhodonite - MnSiO₃
  • Pectolite - NaCa₂(Si₃O₈)(OH)

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)₂
    • Riebeckite (asbestos) - Na₂Fe²⁺₃Fe³⁺₂Si₈O₂₂(OH)₂
    • Arfvedsonite - Na₃(Fe,Mg)₄FeSi₈O₂₂(OH)₂

Phyllosilicates

Phyllosilicates (from Greek φύλλον phyllon, leaf), or sheet silicates, form parallel sheets of silicate tetrahedra with Si₂O₅ or a 2:5 ratio.

Kaolin

• Serpentine group
  • Antigorite - Mg₃Si₂O₅(OH)₄
  • Chrysotile - Mg₃Si₂O₅(OH)₄
  • Lizardite - Mg₃Si₂O₅(OH)₄
• Clay mineral group
  • Halloysite - Al₂Si₂O₅(OH)₄
  • Kaolinite - Al₂Si₂O₅(OH)₄
  • Illite - (K,H₃O)(Al,Mg,Fe)₂(Si,Al)₄O₁₀[(OH)₂,(H₂O)]
  • 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

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.

Archivo:Quartz Crystal.jpg

Quartz

Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). Collected by Apollo 16 from the Lunar Highlands near Descartes Crater.

• Quartz group
  • Quartz - SiO₂
  • Tridymite - SiO₂
  • Cristobalite - SiO₂
• Feldspar group
  • Alkali-feldspars
    • Potassium-feldspars
      • Microcline - KAlSi₃O₈
      • Orthoclase - KAlSi₃O₈
      • Sanidine - KAlSi₃O₈
    • Anorthoclase - (Na,K)AlSi₃O₈
  • 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
• Feldspathoid group
  • Nosean - Na₈Al₆Si₆O₂₄(SO₄)
  • Cancrinite - Na₆Ca₂(CO₃,Al₆Si₆O₂₄).2H₂O
  • Leucite - KAlSi₂O₆
  • Nepheline - (Na,K)AlSiO₄
  • Sodalite - Na₈(AlSiO₄)₆Cl₂
    • Hauyne - (Na,Ca)_4-8Al₆Si₆(O,S)24(SO₄,Cl)_1-2
  • Lazurite - (Na,Ca)₈(AlSiO₄)₆(SO₄,S,Cl)₂
• Petalite - LiAlSi₄O₁₀
• Scapolite group
  • Marialite - Na₄(AlSi₃O₈)₃(Cl₂,CO₃,SO₄)
  • Meionite - Ca₄(Al₂Si₂O₈)₃(Cl₂CO₃,SO₄)
• Analcime - NaAlSi₂O₆•H₂O
• Zeolite group
  • Natrolite - Na₂Al₂Si₃O₁₀•2H₂O
  • Chabazite - CaAl₂Si₄O₁₂•6H₂O
  • Heulandite - CaAl₂Si₇O₁₈•6H₂O
  • Stilbite - NaCa₂Al₅Si₁₃O₃₆•17H₂O

References

• Deer, W.A.; Howie, R.A., & Zussman, J. (1992). An introduction to the rock-forming minerals (2nd ed.). London: Longman. ISBN 0582300940. 

• 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 ed.). London: Geological Society of London. p. 982 pp. 

• Hurlbut, Cornelius S. (1966). Dana's Manual of Mineralogy (17th ed.). ISBN 0-471-03288-3. 

• Hurlbut, Cornelius S.; Klein, Cornelis (1985). Manual of Mineralogy (20th ed.). Wiley. ISBN 0-471-80580-7. 

External links

• Mineral.galleries
• Minerals.net
• Mindat.org, Dana classification
• Webmineral.com

Diccionarios
español: Silicato Deutsch: Silicate italiano: Silicato français : Silicate		English: Silicate minerals 日本語: ケイ酸塩鉱物 português: Silicato (minerais)

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