Silicate minerals are those with more atomic percent silicon oxide than other constituent elements.
For example, kaolinite is Al2Si2O5(OH)4. If aluminum (Al) at two atoms per molecular unit were the most numerous element, kaolinite would be an aluminide.
As the most numerous element is oxygen at 9 for 52.9 at %, kaolin is an oxide. The crystal structure consists of a sheet of interconnected silica tetrahedra. So, kaolin is a phyllosilicate.
Def. the "oxyanion of silicon SiO32- or any salt or mineral containing this ion" is called a metasilicate.
- "any salt or ester of orthosilicic acid, (M+)4SiO44− or Si(OR)4" or
- "any silicate mineral, such as garnet or olivine, in which the SiO4 tetrahedra do not share oxygen atoms with each other"
is called an orthosilicate.
Def. "any simple silicate mineral in which the SiO4 tetrahedra are isolated and have metal ions as neighbours" is called a neosilicate.
Def. a "type of silicate crystal structure characterized by the linking of SiO4 tetrahedra through other cations rather than the sharing of oxygens among SiO4 tetrahedra" is called a nesosilicate.
The second nesosilicate image down on the right is of the mineral sphene. Its molecular formula is CaTiSiO5. Each crystallographic unit cell of sphene contains at least one molecular unit. The actual space group P 21/a has Z=4 (or four molecules per unit cell).
"Sphene is widely distributed as an accessory mineral in intermediate and felsic plutonic rocks, pegmatites and alpine veins, particularly in coarse-grained igneous rocks such as syenite, nepheline syenite, diorite and granodiorite. It occurs similarly in schists or gneisses and in some metamorphosed limestones."
Def. any group of silicates that have structurally isolated double tetrahedra (the dimeric anion Si2O76-) is called a sorosilicate.
Def. any group of silicates that have a ring of linked tetrahedra is called a cyclosilicate.
"Beryl of various colors is found most commonly in granitic pegmatites, but also occurs in mica schists ... Goshenite [a beryl clear to white cyclosilicate] is found to some extent in almost all beryl localities."
Def. "any silicate having interlocking chains of silicate tetrahedra" is called an inosilicate.
To form these chains, each silica tetrahedron shares two oxygens with neighboring tetrahedra.
Single chain tetrahedra are the pyroxenes. Double chains of tetrahedra are the amphiboles.
Anthophyllite is a double-chain inosilicate, or amphibole.
Def. any "silicate mineral having a crystal structure of parallel sheets of silicate tetrahedra" is called a phyllosilicate.
Phyllosilicate tetrahedra share three oxygens with other silica tetrahedra to form two-dimensional sheets.
Def. a type "of silicate crystal structure characterized by the sharing of all SiO4 tetrahedral oxygens resulting in three-dimensional framework structures" is called a tektosilicate.
Def. any "of various silicate minerals ... with a three-dimensional framework of silicate tetrahedra" is called a tectosilicate.
Def. a group of "aluminum silicates [aluminosilicates] of the alkali metals sodium, potassium, calcium and barium" are called feldspars, or feldspar.
"The mineralogical composition of most feldspars can be expressed in terms of the ternary system Orthoclase (KAlSi3O8), Albite (NaAlSi3O8) and Anorthite (CaAl2Si2O8)."
"The minerals of which the composition is comprised between Albite and Anorthite are known as the plagioclase feldspars, while those comprised between Albite and Orthoclase are called the alkali feldspars due to the presence of alkali metals sodium and potassium."
Def. any of a group of silicates "that did not contain enough silica to satisfy all the chemical bonds" of the framework is called a feldspathoid.
The second image down on the right contains analcime, or analcite, as colorless sharply formed undamaged crystals to 25 mm in diameter on a 78 mm x 65 mm x 53 mm matrix. They are associated with numerous black prismatic terminated crystals of aegirine, as well as smaller colorless prismatic terminated crystals of natrolite, these from 3 mm to 10 mm in length. Aegirine is a pyroxene. Natrolite is another feldspathoid like analcime of the zeolite group.
"Feldspar is by far the most abundant group of minerals in the earth's crust, forming about 60% of terrestrial rocks."
- Most minerals on Earth are oxides.
- "metasilicate". San Francisco, California: Wikimedia Foundation, Inc. June 20, 2013. Retrieved 2013-09-02.
- "orthosilicate". San Francisco, California: Wikimedia Foundation, Inc. June 16, 2013. Retrieved 2013-09-02.
- Willard Lincoln Roberts, George Robert Rapp, Jr., and Julius Weber (1974). Encyclopedia of Minerals. 450 West 33rd Street, New York, New York 10001 USA: Van Nostrand Reinhold Company. p. 693. ISBN 0-442-26820-3.
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- J.M. Duke and M. Bonardi (1982). "Chromian andradite from Reaume Township, Ontario". Canadian Mineralogist 20: 49-53. http://rruff.info/doclib/cm/vol20/CM20_49.pdf. Retrieved 2015-10-23.
- "neosilicate". San Francisco, California: Wikimedia Foundation, Inc. June 15, 2013. Retrieved 2013-09-02.
- Martine van der Westhuizen (26 November 2010). "Mineral of the Month - Sphene or Titanite". Bothasig, Cape Town, South Africa 7406: The Cape Town Gem & Mineral Club. Retrieved 2015-08-10.CS1 maint: location (link)
- "sorosilicate". San Francisco, California: Wikimedia Foundation, Inc. June 19, 2013. Retrieved 2013-09-02.
- "Beryl". San Francisco, California: Wikimedia Foundation, Inc. April 15, 2013. Retrieved 2013-05-03.
- "inosilicate". San Francisco, California: Wikimedia Foundation, Inc. 21 June 2013. Retrieved 2013-09-02.
- "phyllosilicate". San Francisco, California: Wikimedia Foundation, Inc. June 17, 2013. Retrieved 2013-09-02.
- "tectosilicate". San Francisco, California: Wikimedia Foundation, Inc. June 17, 2013. Retrieved 2013-09-02.
- Pinkfud (2 November 2004). "feldspar". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2015-07-30.
- IMA-NA (30 July 2015). "What is Feldspar?". North America: Industrial Minerals Association - North America (IMA-NA). Retrieved 2015-07-30.
- Pinkfud (6 November 2004). "feldspathoid, In: Wiktionary". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2015-07-30.