[feld-spahr, fel-]
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.

1750–60; feld- (< German: field) + spar3; replacing feldspath < German (Feld field + Spath spar)

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To feldspar
World English Dictionary
feldspar or felspar (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
[C18: from German feldspat(h), from feld field + spat(h) spar³]
felspar or felspar
[C18: from German feldspat(h), from feld field + spat(h) spar³]
feldspathic or felspar
fel'spathic or felspar
'feldspathose or felspar
'felspathose or felspar

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Cite This Source
Word Origin & History

1757, from Ger. Feldspath, from Feld "field" + spath "spar, non-metallic mineral, gypsum."
Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
American Heritage
Science Dictionary
feldspar   (fěld'spär', fěl'-)  Pronunciation Key 
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.
Cite This Source
Example sentences
Until now, scientists had believed the moon was made of two basic types of rock: dark basalt and light, calcium-rich feldspar.
Andesite is a gray, fine-grained volcanic rock, chiefly composed of plagioclase feldspar.
The coarse feldspar grains enclosed within the enclave are the same as the feldspar grains that make up the granite outside it.
Feldspar in the rock is moderately to intensely altered to sericite and clay minerals.
Image for feldspar
Copyright © 2014 Dictionary.com, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature