feldspar

feld·spar  (fldspär, fl-) also fel·spar (fl-)

n.

Any of a group of abundant rock-forming minerals occurring principally in igneous, plutonic, and some metamorphic rocks, and consisting of silicates of aluminum with potassium, sodium, calcium, and, rarely, barium. About 60 percent of the earth's outer crust is composed of feldspar.

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[Partial translation of obsolete German Feldspath : Feld, field (from Middle High German veld, from Old High German feld; see pel-² in Indo-European roots) + Spath, spar.]

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feldspar or felspar

Noun

a hard mineral that is the main constituent of igneous rocks [German feldspath]

feldspathic
felspathic adj

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feldspar  (fldspär, fl-)

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.

Thesaurus

Noun

1.

feldspar - any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium felspar atomic number 14, Si, silicon - a tetravalent nonmetallic element; next to oxygen it is the most abundant element in the earth's crust; occurs in clay and feldspar and granite and quartz and sand; used as a semiconductor in transistors orthoclase - a white or colored monoclinic feldspar oligoclase, plagioclase - any of a series of triclinic feldspars that form rocks moonstone - a transparent or translucent gemstone with a pearly luster; some specimens are orthoclase feldspar and others are plagioclase feldspar spar - any of various nonmetallic minerals (calcite or feldspar) that are light in color and transparent or translucent and cleavable