feldspar

American

[feld-spahr, fel-] / ˈfɛldˌspɑr, ˈfɛl- /

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.

feldspar British

/ ˈfɛldˌspɑː, fɛldˈspæθɪk, ˈfɛlˌspɑː, fɛlˈspæθ- /

noun

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

"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

feldspar Scientific

/ fĕld′spär′,fĕl′- /

Any of a group of abundant monoclinic or triclinic minerals having the general formula MAl(Al,Si) ₃ O ₈, 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.

Other Word Forms

Derived Forms

feldspathic

adjective

Etymology

Origin of feldspar

1750–60; feld- (< German: field) + spar ³; replacing feldspath < German ( Feld field + Spath spar)

Vocabulary lists containing feldspar

Earth Science - Middle School

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2015 Spelling Bee - Words from Round 2

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Earth Science - High School

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Feldspar is a ubiquitous mineral and makes up about half of the Earth's crust.

From Science Daily • Jan. 9, 2024

Feldspar does not have any argon in it when it forms.

From Textbooks • Jan. 1, 2015

“But Lon came out and retrieved me from Feldspar that time I had a flat.”

From The New Yorker • Jun. 6, 2011

Feldspar, of hardness 6, hence slightly softer than a file and yielding to it, but scratching the stones likewise rated as 6 when applied forcibly to them.

From A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public by Wade, Frank Bertram

Feldspar, for example, has the formula KAlSi3O8, and is a mixed salt of the acid H4Si3O8, whose formation is represented in the equation above.

From An Elementary Study of Chemistry by McPherson, William

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023