felsic(redirected from Acid rock (geology))
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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.
(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