amphibolite

A Dictionary of Earth Sciences | 1999 | 558 words | Copyright

amphibolite A medium-grained, dark-coloured, regional metamorphic rock composed of hornblende and plagioclase with minor epidote, sphene, biotite, and quartz. The rock may show a well developed planar or linear alignment of elongate hornblende crystals as a result of suffering deformation at the same time as regional metamorphism. These alignments define fabrics within the rock known as schistosity and lineation respectively. Amphibolites are formed by medium-grade metamorphism of basic igneous rocks such as basalts, both extrusive and intrusive types.

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AILSA ALLABY and MICHAEL ALLABY. "amphibolite." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

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AILSA ALLABY and MICHAEL ALLABY. "amphibolite." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-amphibolite.html