essential mineral

A Dictionary of Earth Sciences | 1999 | 401 words | Copyright

essential mineral A primary mineral whose presence in an igneous rock is essential to defining the root name of that rock. For example, plagioclase and the pyroxene augite are essential to defining the root name ‘gabbro’ and hence are essential minerals. Where a primary mineral is present but is not essential to the naming of the rock it is termed an ‘accessory mineral’.

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AILSA ALLABY and MICHAEL ALLABY. "essential mineral." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "essential mineral." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O13-essentialmineral.html

AILSA ALLABY and MICHAEL ALLABY. "essential mineral." A Dictionary of Earth Sciences. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-essentialmineral.html

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