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Longman Dictionary of Contemporary English
feldspar
noun
EXAMPLES FROM CORPUS
▪ Ankerite, haematite, mica and feldspar have also been identified in smaller quantities.
▪ Electron microprobe element maps show the distribution and quantity of alkali feldspar in the fine-grained groundmass of the altered basalts.
▪ Finally, a temperature is reached when a third mineral, feldspar, joins in.
▪ If feldspar is present, it is in minor volumes or traces.
▪ Petrological observations show excess feldspar in many basaltic lavas which is most easily explained by crystal settling.
▪ Quartz, feldspar, and the clay minerals make up the bulk of that contribution.
▪ They contain large amounts of the feldspar mineral.
The Collaborative International Dictionary
Feldspar

Feldspar \Feld"spar`\, Feldspath \Feld"spath`\, n. [G. feldspath; feld field + spath spar.] (Min.) A name given to a group of minerals, closely related in crystalline form, and all silicates of alumina with either potash, soda, lime, or, in one case, baryta. They occur in crystals and crystalline masses, vitreous in luster, and breaking rather easily in two directions at right angles to each other, or nearly so. The colors are usually white or nearly white, flesh-red, bluish, or greenish.

Note: The group includes the monoclinic (orthoclastic) species orthoclase or common potash feldspar, and the rare hyalophane or baryta feldspar; also the triclinic species (called in general plagioclase) microcline, like orthoclase a potash feldspar; anorthite or lime feldspar; albite or soda feldspar; also intermediate between the last two species, labradorite, andesine, oligoclase, containing both lime and soda in varying amounts. The feldspars are essential constituents of nearly all crystalline rocks, as granite, gneiss, mica, slate, most kinds of basalt and trachyte, etc. The decomposition of feldspar has yielded a large part of the clay of the soil, also the mineral kaolin, an essential material in the making of fine pottery. Common feldspar is itself largely used for the same purpose.

Douglas Harper's Etymology Dictionary
feldspar

type of mineral common in crystalline rocks, 1785, earlier feldspath (1757), from older 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." Related: Feldspathic.

Wiktionary
feldspar

n. (context mineral English) Any of a large group of rock-forming minerals that, together, make up about 60% of the earth's outer crust. The feldspars are all aluminum silicates of the alkali metals sodium, potassium, calcium and barium. Feldspars are the principal constituents of igneous and plutonic rocks.

WordNet
feldspar

n. any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium [syn: felspar]

Wikipedia
Feldspar

Feldspars ( K Al Si O – Na Al Si O – Ca Al Si O) are a group of rock-forming tectosilicate minerals that make up as much as 60% of the Earth's crust.

Feldspars crystallize from magma as veins in both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Rock formed almost entirely of calcic plagioclase feldspar (see below) is known as anorthosite. Feldspars are also found in many types of sedimentary rocks.

Feldspar (disambiguation)

Feldspar is a group of rock-forming minerals including

  • Alkali feldspar
  • Alkali feldspar granite
  • Potassium feldspar

Feldspar may also refer to

  • Community in Tay Valley, Ontario, Canada
  • USS Feldspar (IX-159), a concrete barge
  • Craig Feldspar, a character in the American television comedy series Malcolm in the Middle

Usage examples of "feldspar".

Oswald Brunies, the strutting, candy-sucking teacher -- a monument will be erected to him -- to him with magnifying glass on elastic, with sticky bag in sticky coat pocket, to him who collected big stones and little stones, rare pebbles, preferably mica gneiss -- muscovy biotite -- quartz, feldspar, and hornblende, who picked up pebbles, examined them, rejected or kept them, to him the Big Playground of the Conradinum was not an abrasive stumbling block but a lasting invitation to scratch about with the tip of his shoe after nine rooster steps.

Kemjawi as a byproduct of feldspar mining, and phlogopite at Siilinjarvi from an apatite mine.

Triassic red sand, acidic volcanics, pink feldspar, green chlorite, ironstone, grit, sand and silt.

The name was taken from the Chinese mountain of Kailing, where the first kaolin, or decomposed feldspar, was found.

There was no furniture as such, only stands and cases and pedestals, likewise all of polished stone: jadeite, nephrite, agate, feldspar and onyx, glabrous gray chalcedony.

The coarse-grained friable sandstone, in which the lodges have been excavated, consists chiefly of subangular and rounded grains of quartz and feldspar with a small proportion of black particles.

And that rock is very much like lunar highlands material: basically plagioclase feldspar, a calcium-aluminum silicate.

We can also extract aluminum from plagioclase, which is a kind of feldspar you find in the highlands.

This new thermoluminescence method can aid in determining the age of limestone and other rocks, such as dolomite, quartz, fluorite, and the feldspars, which are highly thermoluminescent.

Monsieur Bianchi had patiently pushed aside masses of banal quartz, chalk or feldspar, feeling at any less banal pebble with his yellow thumbnail, lifting up his glasses and squinting because of the smoke from his maize-papered cigarette that was always in his scruffy mouth: his razorblades were as stale as his toothbrush.

Oswald Brunies, the strutting, candy-sucking teacher -- a monument will be erected to him -- to him with magnifying glass on elastic, with sticky bag in sticky coat pocket, to him who collected big stones and little stones, rare pebbles, preferably mica gneiss -- muscovy biotite -- quartz, feldspar, and hornblende, who picked up pebbles, examined them, rejected or kept them, to him the Big Playground of the Conradinum was not an abrasive stumbling block but a lasting invitation to scratch about with the tip of his shoe after nine rooster steps.

And that rock is very much like lunar highlands material: basically plagioclase feldspar, a calcium-aluminum silicate.

Austell has reason to be glad of that, for without decomposed feldspar there would be no treasure house of china clay.

In the afternoon he sat in the compound breaking ore samples with a hammer, the feldspar rich in red oxide of copper and native nuggets in whose organic lobations he purported to read news of the earth's origins, holding an extemporary lecture in geology to a small gathering who nodded and spat.

In fact, locked up in Cruithne there were also troilite, olivine, pyroxene, and feldspar -- minerals that could also serve as sources of ferrous metals when the nickel-iron was exhausted, even if their extraction was a little more complex.