Silicate minerals

From Wikipedia, the free encyclopedia
Silicate minerals

Copper silicate mineral chrysocolla
Category Mineral

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 which contain different ratios of silicon and oxygen.

Nesosilicates or orthosilicates

Nesosilicate specimens at the Museum of Geology in South Dakota

Nesosilicates (from Greek νησος nēsos, island), or orthosilicates, have isolated (insular) [SiO4]4− tetrahedra that are connected only by interstitial cations. Nickel-Strunz classification: 09.A

Kyanite crystals (unknown scale)

Sorosilicates

Sorosilicate exhibit at Museum of Geology in South Dakota

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

Cyclosilicates

Cyclosilicate specimens at the Museum of Geology, South Dakota

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

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

Inosilicates (from Greek ις is [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. Nickel-Strunz classification: 09.D

Single chain inosilicates

Double chain inosilicates

  • 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

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

Kaolin

  • 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

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

Gallery

  • Nesosilicate (SiO4)

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

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

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

See also

Further references

    • Deer, W.A.; Howie, R.A., & Zussman, J. (1992). An introduction to the rock-forming minerals (2nd ed.). London: Longman. ISBN 0-582-30094-0. 
    • 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

    Media related to Silicates at Wikimedia Commons

    This article is issued from Wikipedia. The text is available under the Creative Commons Attribution/Share Alike; additional terms may apply for the media files.