feldspars

feldspar

[feld-spahr, fel-]
noun
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:
1750–60; feld- (< German: field) + spar3; replacing feldspath < German (Feld field + Spath spar)

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Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
feldspar or felspar (ˈfɛldˌspɑː, ˈfɛlˌspɑː)
 
n
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
 
n
 
[C18: from German feldspat(h), from feld field + spat(h) spar³]
 
feldspathic or felspar
 
adj
 
fel'spathic or felspar
 
adj
 
'feldspathose or felspar
 
adj
 
'felspathose or felspar
 
adj

Collins English Dictionary - Complete & Unabridged 10th Edition
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Etymonline
Word Origin & History

feldspar
1757, from Ger. Feldspath, from Feld "field" + spath "spar, non-metallic mineral, gypsum."
Online Etymology Dictionary, © 2010 Douglas Harper
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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
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