What is Hornblende?
[[File:Amphibole.jpg|thumb|right|220px|Amphibole hornblende]] '''Hornblende''' is a complex series of [[silicate]] [[mineral]]s.<ref>http://www.mindat.org/min-8789.html Mindat</ref> Hornblende is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark [[amphibole]]. It is an isomorphous mixture of three [[molecule]]s; a [[calcium]]-[[iron]]-[[magnesium]] silicate, an [[aluminium]]-iron-magnesium silicate, and an iron-magnesium silicate. Hornblende has a [[Mohs scale of mineral hardness|hardness]] of 5–6, a [[specific gravity]] of 2.9–3.4 and is typically an opaque green, greenish-brown, brown or black color. It is most often confused with the minerals [[augite]] and [[biotite]] mica, both of which are black and can be found in [[granite]]. ==Occurrence== Hornblende is a common constituent of many [[igneous rock|igneous]] and [[metamorphic rock]]s such as [[granite]], [[diorite]], [[gabbro]], [[basalt]], [[andesite]], [[gneiss]], and [[schist]]. It is the principal mineral of [[amphibolite]]s. Very dark brown to black hornblendes that contain titanium may be called [[basalt]]ic hornblende, from the fact that they are usually a constituent of basalt and related rocks. ==Etymology== The word hornblende is derived from the [[German language|German]] ''horn'' and ''blenden'', to 'blind' or 'dazzle'. The term ''blende'' is often used to refer to a brilliant non-metallic [[lustre (mineralogy)|luster]], for example, [[zinc]]blende and [[pitchblende]], the [[ore]] of [[uranium]]. ==Related pages== *[[List of minerals]] ==References== {{Reflist}} * Hurlbut, Cornelius S.; Klein, Cornelis, 1985, ''Manual of Mineralogy'', 20th ed., John Wiley and Sons, New York, p 416-7, {{ISBN|0-471-80580-7}} *[http://www.mindat.org/min-1930.html Mindat] retrieved 06/21/05 *[http://www.geology.neab.net/minerals/hornblen.htm Scandinavian mineral gallery] {{Webarchive|url=https://web.archive.org/web/20100502024415/http://www.geology.neab.net/minerals/hornblen.htm |date=2010-05-02