felsic

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fel·sic

 (fĕl′sĭk)
adj.
Relating to or containing a group of light-colored silicate minerals that occur in igneous rocks, including minerals of the feldspathoid group and the minerals quartz, feldspar, and muscovite.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

felsic

(ˈfɛlsɪk)
adj
(of minerals) predominantly composed of feldspars or silicates
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014