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hornblende
hornblende An important rock-forming silicate mineral and member of the amphiboles, particularly the calcium-rich monoclinic amphiboles; it is the general name given to a group of amphiboles (the hornblende series) with similar properties, which includes hastingsite Ca2(Mg4Al)[Si7AlO22](OH,F)2, tschermakite Ca2(Mg3AL2)[Si6Al2O22](OH,F)2, edenite NaCa2Mg5 [Si6AlO22] (OH, F)2, and pargasite NaCa2(Mg4Al) [Si6Al2O22](OH,F)2; sp. gr. 3.0–3.5; hardness 5.0–6.0; black or greenishblack; white streak with a greenish tint; vitreous lustre; crystals normally prismatic, columnar, and occasionally isometric; cleavages in two directions set at 1240, prismatic {110}; occurs as a common constituent of medium basic, igneous rocks (e.g. syenites, diorites, and granodiorites), also in contact metasomatic zones, and extensively in metamorphic rocks (e.g. schists, gneisses, and amphibolites).
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AILSA ALLABY and MICHAEL ALLABY. "hornblende." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "hornblende." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-hornblende.html AILSA ALLABY and MICHAEL ALLABY. "hornblende." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-hornblende.html |
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hornblende
horn·blende / ˈhôrnˌblend/ • n. a dark brown, black, or green mineral of the amphibole group consisting of a hydroxyl alumino-silicate of calcium, magnesium, and iron, occurring in many igneous and metamorphic rocks. |
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"hornblende." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "hornblende." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O999-hornblende.html "hornblende." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-hornblende.html |
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hornblende
hornblende Black or green mineral found in igneous and metamorphic rocks. It is the commonest form of amphibole, and contains iron and silicates of calcium, aluminium and magnesium. Hardness 5.5; r.d. 3.2.
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"hornblende." World Encyclopedia. 2005. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "hornblende." World Encyclopedia. 2005. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O142-hornblende.html "hornblende." World Encyclopedia. 2005. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-hornblende.html |
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hornblende
hornblende see amphibole . |
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Cite this article
"hornblende." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "hornblende." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1E1-X-hornblen.html "hornblende." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-X-hornblen.html |
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