Silicate minerals

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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.

1 Nesosilicates or orthosilicates
2 Sorosilicates
3 Cyclosilicates
4 Inosilicates
- 4.1 Single chain inosilicates
- 4.2 Double chain inosilicates
5 Phyllosilicates
6 Tectosilicates
7 References
8 External links

Nesosilicates or orthosilicates

Nesosilicates, 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

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, 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.

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 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 0-471-03288-3.

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

External links

Categories: Minerals | Silicate minerals

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