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[feld-spahr, fel-] /ˈfɛldˌspɑr, ˈfɛl-/
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.
Also, felspar.
Origin of feldspar
1750-60; feld- (< German: field) + spar3; replacing feldspath < German (Feld field + Spath spar) Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for feldspar
Historical Examples
  • The ingredients in alkaline glazes are soda-ash, whiting, feldspar, flint and oxide of tin.

    The Potter's Craft Charles F. Binns
  • Granite is made of quartz, mica, and feldspar, as has been said before.

    Diggers in the Earth Eva March Tappan
  • Pick up a handful of gravel and you will be able to find much of it feldspar or other mineral containing some ten per cent.

    Creative Chemistry Edwin E. Slosson
  • feldspar as an abrasive is used mainly in scouring soaps and window-wash.

  • It had been taken away with a feldspar to the china factory, and only when there was no more to be got, man had stayed away.

    The Confession of a Fool August Strindberg
  • I do hope I 'll get one with feldspar in it, or something nice and interesting.

    The Wrong Woman Charles D. Stewart
  • We knew that the place was ugly and sinister, but feldspar and augite didn't give it that look.

    The White Waterfall James Francis Dwyer
  • When flint and feldspar are used, they are ground fine at the quarry.

    Makers of Many Things Eva March Tappan
  • The appearance of the rock is not modified by the amount of feldspar which it contains.

  • According to the color of the feldspar the rock may be red, or pink, or gray.

    The Elements of Geology William Harmon Norton
British Dictionary definitions for feldspar


/ˈfɛldˌspɑː; ˈfɛlˌspɑː/
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
Derived Forms
feldspathic (fɛldˈspæθɪk; fɛlˈspæθ-), felspathic, feldspathose, felspathose, adjective
Word Origin
C18: from German feldspat(h), from feld field + spat(h) spar³
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
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Word Origin and History for feldspar

1785, earlier feldspath (1757), from German Feldspath (Modern German Feldspat), from Feld "field" (see field (n.)) + spath "spar, non-metallic mineral, gypsum" (see spar (n.2)); spelling influenced by English spar "mineral."

Online Etymology Dictionary, © 2010 Douglas Harper
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feldspar in Science
  (fěld'spär', fěl'-)   
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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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