Sillimanite

Sillimanite

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Sillimanite also called Bucholzite is an alumino-silicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman (1779-1864).

Occurrence

Sillimanite is one of three alumino-silicate polymorphs, the other two being andalusite and kyanite. A common variety of sillimanite is known as "fibrolite", so named because the mineral appears like a bunch of fibres twisted together when viewed under thin section or even by the naked eye. Both the fibrous and traditional forms of sillimanite are common in metamorphosed sedimentary rocks. It is an index mineral indicating high-temperature metamorphism.

Sillimanite has been found in Brandywine Springs, New Castle County, Delaware, USA. By suggestion of the members of the [http://www.delminsociety.net/ Delaware Mineralogical Society] , it was named by the State Legislature in 1977 as the [http://www.udel.edu/dgs/Education/sillimanite.html Official Mineral of Delaware] .

Details

Crystallographic systemOrthorhombic
ColoursWhite, brown and green
LustreSilky if in fibrous form, else vitreous
Hardness7.5
Refractive index 1.641-1.648
Cleavage1
Twinningn/a
PleochroismColourless to pale brown to yellow
Type localityVltava, Susice, Czech Republic.

ee also

*Andalusite
*Kyanite
*List of minerals
*List of minerals named after people

External links

* [http://webmineral.com/data/Sillimanite.shtml WebMineral entry]


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Look at other dictionaries:

  • Sillimanite — Sillimanite[1] Catégorie IX : silicates[2] S …   Wikipédia en Français

  • SILLIMANITE — Avec le disthène et l’andalousite, la sillimanite (du nom de Benjamin Silliman) fait partie du groupe des silicates d’alumine anhydres. C’est un subnésosilicate, c’est à dire que la trame cristalline est constituée d’octaèdres Al6 ayant leurs… …   Encyclopédie Universelle

  • Sillimanite — Sil li*man*ite, n. [After Benjamin Siliman, an American meneralogist.] (Min.) Same as {Fibrolite}. [1913 Webster] …   The Collaborative International Dictionary of English

  • sillimanite — ☆ sillimanite [sil′ə mə nīt΄ ] n. [after B. Silliman (1779 1864), U.S. chemist and geologist + ITE1] a very hard, mineral, aluminum silicate, Al2SiO5, usually found in metamorphic rock as long, slender crystals of various colors …   English World dictionary

  • sillimanite — /sil euh meuh nuyt /, n. a mineral, aluminum silicate, Al2SiO5, occurring in the form of long, slender, and often fibrous crystals. Also called fibrolite. [1825 30; named after B. SILLIMAN; see ITE1] * * * or fibrolite Brown, pale green, or white …   Universalium

  • sillimanite — Fibrolite Fi bro*lite (? or ?), n. [L. fibra a fiber + lite: cf. F. fibrolithe.] (Min.) A silicate of alumina, of fibrous or columnar structure. It is like andalusite in composition; called also {sillimanite}, and {bucholizite}. [1913 Webster] …   The Collaborative International Dictionary of English

  • sillimanite — silimanitas statusas T sritis chemija apibrėžtis Mineralas. formulė Al₂[O|SiO₄] atitikmenys: angl. sillimanite rus. силлиманит …   Chemijos terminų aiškinamasis žodynas

  • sillimanite group — noun : the group of minerals comprising sillimanite, cyanite, andalusite, dumortierite, topaz, and mullite …   Useful english dictionary

  • sillimanite — noun Etymology: Benjamin Silliman died 1864 American geologist Date: circa 1830 a brown, grayish, or pale green mineral that consists of an aluminum silicate in orthorhombic crystals often occurring in fibrous or columnar forms …   New Collegiate Dictionary

  • sillimanite — noun A fibrous neosilicate mineral, polymorphic with andalusite and kyanite, with the chemical formula AlSiO …   Wiktionary

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