Staurolite

Staurolite

Staurolite is a red brown to black, mostly opaque, nesosilicate mineral with a white streak. It crystallizes in the monoclinic crystal system, has a Mohs hardness of 7 to 7.5 and a rather complex chemical formula: (Fe,Mg,Zn)2Al9(Si,Al)4O20(OH)4. Iron, magnesium and zinc occur in variable ratios.

A special property of staurolite is that it often occurs twinned in a characteristic cross-shape. In handsamples, macroscopically visible staurolite crystals are of prismatic shape. They are often larger than the surrounding minerals and are then called porphyroblasts.

In thin sections staurolite is commonly twinned and shows lower first order birefringence similar to quartz, with the twinning displaying optical continuity. It can be identified in metamorphic rocks by its swiss cheese appearance (with poikilitic quartz) and often manteld porphyroblastic character.

The name is derived from the Greek, "stauros" for cross and "lithos" for stone in reference to the common twinning. Staurolite is a regional metamorphic mineral of intermediate to high grade. It occurs with almandine garnet, micas, kyanite and other metamorphic minerals.

It is the official state mineral of the United States state of Georgia.

Staurolite is one of the index minerals that are used to estimate the temperature, depth, and pressure at which a rock undergoes metamorphism.

References

* [http://webmineral.com/data/Staurolite.shtml Webmineral]
* [http://www.mindat.org/show.php?id=3753&ld=1&pho= Mindat w/ locations]
* [http://mineral.galleries.com/minerals/silicate/stauroli/stauroli.htm Mineral galleries]


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  • Staurolite — Catégorie IX : silicates[1] Staurolite Russie Général …   Wikipédia en Français

  • Staurolite — Stau ro*lite (st[add] r[ o]*l[imac]t), n. [Gr. stayro s a cross + lite.] (Min.) A mineral of a brown to black color occurring in prismatic crystals, often twinned so as to form groups resembling a cross. It is a silicate of alumina and iron, and… …   The Collaborative International Dictionary of English

  • staurolite — [stôr′ə līt΄] n. [Fr < Gr stauros, a cross, post < IE * steu > ON staurr, post (see STORE) + lite, LITE] a dark colored mineral, (Fe,Mg) 2Al9Si4O23 (OH), a silicate of iron and aluminum: the crystals are often found twinned in the form… …   English World dictionary

  • staurolite — staurolitic /stawr euh lit ik/, adj. /stawr euh luyt /, n. a mineral, basic iron aluminum silicate, Fe2Al2O7(SiO4)4(OH), occurring in brown to black prismatic crystals, which are often twinned in the form of a cross. [1790 1800; < Gk stauró(s) a… …   Universalium

  • staurolite — ● staurotide ou staurolite nom féminin Silicate naturel d aluminium et de fer, orthorhombique. (La macle la plus fréquente de ce minerai porte le nom de pierre de croix ou croisette de Bretagne.) …   Encyclopédie Universelle

  • staurolite — staurolitas statusas T sritis chemija apibrėžtis Mineralas. formulė 4Al₂O·[SiO₄]AlFe₂O₃(OH) atitikmenys: angl. staurolite rus. ставролит …   Chemijos terminų aiškinamasis žodynas

  • staurolite — noun Etymology: French, from Greek stauros cross + French lite more at steer Date: circa 1815 a mineral consisting of a basic silicate of iron and aluminum in prismatic orthorhombic crystals often twinned so as to resemble a cross • staurolitic… …   New Collegiate Dictionary

  • staurolite — noun A dark brown nesosilicate mineral that has crystals that cross and intergrow …   Wiktionary

  • staurolite — stau·ro·lì·te s.f. TS mineral. minerale caratteristico di alcune rocce metamorfiche, costituito da allumosilicato, magnesio e zinco, che cristallizza nel sistema rombico formando geminati a croce di colore rosso scuro {{line}} {{/line}} DATA:… …   Dizionario italiano

  • staurolite — n. 1. See staurotide. 2. Harmotome …   New dictionary of synonyms

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