Silicate minerals

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Silicate minerals
Chrysocolla.jpg
Copper silicate mineral chrysocolla
Category Mineral
"Orthosilicate" redirects here. For anion, see Orthosilicate (ion).

Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of rock-forming minerals and make up approximately 90 percent of the Earth's crust.[1] They are classified based on the structure of their silicate groups, which contain different ratios of silicon and oxygen.

Nesosilicates or orthosilicates[edit]

Basic (ortho-)silicate anion structure
Nesosilicate specimens at the Museum of Geology in South Dakota
Main category: Nesosilicates

Nesosilicates (from Greek νῆσος nēsos, island), or orthosilicates, have the orthosilicate ion, which constitute isolated (insular) [SiO4]4− tetrahedra that are connected only by interstitial cations. Nickel–Strunz classification: 09.A

Examples are:

Kyanite crystals (unknown scale)

Sorosilicates[edit]

Sorosilicate exhibit at Museum of Geology in South Dakota
Main category: Sorosilicates

Sorosilicates (from Greek σωρός sōros, heap, mound) have isolated double tetrahedra groups with (Si2O7)6− or a ratio of 2:7. Nickel–Strunz classification: 09.B

Examples are:

Cyclosilicates[edit]

Cyclosilicate specimens at the Museum of Geology, South Dakota
Main category: Cyclosilicates

Cyclosilicates (from Greek κύκλος kuklos, circle), or ring silicates, have linked tetrahedra with (TxO3x)2x− or a ratio of 1:3. These exist as 3-member (T3O9)6− and 6-member (T6O18)12− rings, where T stands for a tetrahedrally coordinated cation. Nickel–Strunz classification: 09.C

Examples are:

Note that the ring in axinite contains two B and four Si tetrahedra and is highly distorted compared to the other 6-member ring cyclosilicates.

  • Cyclosilicate, [Si6O18] – 6-membered single rings, beryl (red: Si, blue: O)

  • Cyclosilicate, [Si3O9] – 3-membered single ring, benitoite

  • Cyclosilicate, [Si4O12] – 4-membered single ring, papagoite

  • Cyclosilicate, [Si9O27] – 9-membered ring, eudialyte

  • Cyclosilicate, [Si6O18] – 6-membered double ring, milarite

Inosilicates[edit]

Main category: Inosilicates

Inosilicates (from Greek ἴς is [genitive: ἰνός 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. Nickel–Strunz classification: 09.D

Examples are:

Single chain inosilicates[edit]

Double chain inosilicates[edit]

  • Inosilicate, pyroxene family, with 2-periodic single chain (Si2O6), diopside

  • Inosilicate, clinoamphibole, with 2-periodic double chains (Si4O11), tremolite

  • Inosilicate, unbranched 3-periodic single chain of wollastonite

  • Inosilicate with 5-periodic single chain, rhodonite

  • Inosilicate with cyclic branched 8-periodic chain, pellyite

Phyllosilicates[edit]

Main category: Phyllosilicates

Phyllosilicates (from Greek φύλλον phyllon, leaf), or sheet silicates, form parallel sheets of silicate tetrahedra with Si2O5 or a 2:5 ratio. Nickel–Strunz classification: 09.E. All phyllosilicate minerals are hydrated, with either water or hydroxyl groups attached.

Kaolinite

Examples are:

  • Phyllosilicate, mica group, muscovite (red: Si, blue: O)

  • Phyllosilicate, single net of tetrahedra with 4-membered rings, apophyllite-(KF)-apophyllite-(KOH) series

  • Phyllosilicate, single tetrahedral nets of 6-membered rings, pyrosmalite-(Fe)-pyrosmalite-(Mn) series

  • Phyllosilicate, single tetrahedral nets of 6-membered rings, zeophyllite

  • Phyllosilicate, double nets with 4- and 6-membered rings, carletonite

Tectosilicates[edit]

Main category: 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. Nickel–Strunz classification: 09.F and 09.G, 04.DA (Quartz/ silica family)

Quartz
Lunar ferroan anorthosite (plagioclase feldspar) collected by Apollo 16 astronauts from the Lunar Highlands near Descartes Crater

Examples are:

Gallery[edit]

  • Nesosilicate (SiO4)

  • Sorosilicate (Si2O7), as in suolunite
    [Ca2Si2O5(OH)2·H2O]

  • Tectosilicate, aluminosilicate 3D network, zeolite family, synthetic zeolite ZSM-5

  • Silica family (SiO2 3D network), β-quartz

See also[edit]

Further references[edit]

  1. ^ https://www.britannica.com/science/mineral-chemical-compound/Silicates
  • 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[edit]

Media related to Silicates at Wikimedia Commons

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