- any of a group of minerals, principally aluminosilicates of potassium, sodium, and calcium, characterized by two cleavages at nearly right angles: one of the most important constituents of igneous rocks.
Origin of feldspar
1750–60; feld- (< German: field) + spar3; replacing feldspath < German (Feld field + Spath spar)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for feldspar
I do hope I 'll get one with feldspar in it, or something nice and interesting.The Wrong Woman
Charles D. Stewart
Granite is made of quartz, mica, and feldspar, as has been said before.Diggers in the Earth
Eva March Tappan
Feldspar as an abrasive is used mainly in scouring soaps and window-wash.The Economic Aspect of Geology
C. K. Leith
When flint and feldspar are used, they are ground fine at the quarry.Makers of Many Things
Eva March Tappan
According to the color of the feldspar the rock may be red, or pink, or gray.The Elements of Geology
William Harmon Norton
- any of a group of hard rock-forming minerals consisting of aluminium silicates of potassium, sodium, calcium, or barium: the principal constituents of igneous rocks. The group includes orthoclase, microcline, and the plagioclase minerals
C18: from German feldspat (h), from feld field + spat (h) spar ³
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for feldspar
Online Etymology Dictionary, © 2010 Douglas Harper
- Any of a group of abundant monoclinic or triclinic minerals having the general formula MAl(Al,Si)3O8, where M is either potassium (K), sodium (Na), or calcium (Ca) or less commonly barium (Ba), rubidium (Rb), strontium (Sr), or iron (Fe). Feldspars range from white, pink, or brown to grayish blue in color. They occur in igneous, sedimentary, and metamorphic rocks and make up more than 60 percent of the Earth's crust. When they decompose, feldspars form clay or the mineral kaolinite.
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