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.

Origin of feldspar

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

Also felspar.

Words Nearby feldspar

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use feldspar in a sentence

Sienite and feldspar succeeded in our descent to the snow line, where we found a felspathic granite.
The Life of Kit Carson | Edward S. Ellis
The feldspar exhibited its splendent black crystals in fine relief in the massy quartz.
Summary Narrative of an Exploratory Expedition to the Sources of the Mississippi River, in 1820 | Henry Rowe Schoolcraft
What little feldspar there was is reduced to quartz and mica, and the quartz pebbles are drawn out into lenses.
History and Comprehensive Description of Loudoun County, Virginia | James W. Head
This was materially assisted by the weak lath shapes of the feldspar and the mobility of the micas.
History and Comprehensive Description of Loudoun County, Virginia | James W. Head
The appearance of the rock is not modified by the amount of feldspar which it contains.
History and Comprehensive Description of Loudoun County, Virginia | James W. Head

British Dictionary definitions for feldspar

feldspar

felspar

/ (ˈfɛldˌspɑː, ˈfɛlˌspɑː) /

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

Origin of feldspar

C18: from German feldspat (h), from feld field + spat (h) spar ³

Derived forms of feldspar

feldspathic (fɛldˈspæθɪk, fɛlˈspæθ-), felspathic, feldspathose or felspathose, adjective

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

Scientific definitions for feldspar

feldspar

[ fĕld′spär′, fĕl′- ]

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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