feldspar

[ feld-spahr, fel- ]

noun

1. 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

/ ˈfɛldˌspɑː; fɛldˈspæθɪk; ˈfɛlˌspɑː; fɛlˈspæθ- /

noun

1. 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

feldspar

/ fĕld′spär′,fĕl′- /

1. 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.

Derived Forms

• feldspathic, adjective

Word History and Origins

Origin of feldspar¹

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

Word History and Origins

Origin of feldspar¹

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

Example Sentences

Tarduno and his team used innovative strategies and techniques to examine the strength of the magnetic field by studying magnetism locked in ancient feldspar and pyroxene crystals from the rock anorthosite.

From Science Daily

In the Earth's atmosphere, feldspars play a surprisingly important role.

From Science Daily

The researchers also used a technique called optically stimulated luminescence to determine when grains of quartz and feldspar in the adjacent sediments were last exposed to sunlight.

From Scientific American

Luminescence dating normally relies on quartz, but for this study the researchers turned to feldspar, which can absorb much more radioactivity than quartz.

From Science Magazine

Their research indicates that the DNA molecules can cling to minerals of feldspar and clay, which protect them from further damage.

From New York Times